Aroni Nina and Where Bullpen Dominance Comes From

Like many minor league/prospect columnists, I try to see as much live baseball and as many minor league players as I can. Typically, I catch four or five games a week during the minor league season. It can be a bit of a grind at times, but I keep at it for two reasons: First, I want to be able to have the best and most far-reaching coverage I can, and second, because I’m usually having an awesome time doing it.

Of course, some games are more fun to attend from a scouting perspective than others. It’s a lot more exciting to take in the raw power of Joey Gallo, the blinding speed of Terrance Gore, the sweet swing of Francisco Lindor, or the arm strength of Eddie Butler than it is to watch 23-year-old Appalachian League middle relievers throw 84-mph fastballs to 23-year-old Appalachian League utility players. As such, I try to optimize my time and attend games that have the best likelihood of featuring interesting prospects, especially the starting pitchers. Typically, this decision is informed by some combination of the statistics, draft/prospect status, and reported tools/stuff of the players in question–in a way, I’m using a crude version of the same ideas behind our own Carson Cistulli’s NERD scores.

It’s a tremendous feeling to see a prospect in person and have them live up to what their statistics and reputation suggest they should look like. I heard all year about Atlanta’s Mauricio Cabrera and his triple-digit heat, so it was great to see him in person and watch a radar gun read “100” when I finally managed to catch one of his starts in August. Likewise, it’s disappointing to see a player underperform expectations. However, the most amazing experiences I have at games come when a player who’s way off the radar–uninteresting numbers and no scouting buzz–suddenly commands the most rapt attention. It doesn’t happen often, but it does happen, and today I want to share one of my experiences with the phenomenon and tie it in with some of our beliefs about the way players–in particular, relief pitchers–ascend to MLB relevance.

I started frequently attending minor league games in July of 2012, and it was the following month that I first encountered an instance of this experience. It was August 19th, and I was watching the West Virginia Power take on the Kannapolis Intimidators. I was mostly there to see West Virginia starter Nick Kingham and shortstop Alen Hanson and Kannapolis outfielder Courtney Hawkins, with a bit of an eye toward Kannapolis starter Bryan Blough and his then-44/8 K/BB ratio. Hanson was great, Kingham was solid, Blough was okay, and I didn’t get to see Hawkins do much, but the player who made the biggest impression entered the game in the top of the sixth inning. When he was announced, I vaguely recognized the name because he was a trade throw-in the previous offseason. He was a relief pitcher who had turned 23 the previous day, making him quite old for the Low-A South Atlantic League, and he entered the late-season outing with a 6.37 ERA and mediocre peripherals (38/23 K/BB in 53 2/3 IP). Batters were hitting .306/.375/.434 off him.

Then that pitcher threw two innings, showing off a mid-90s fastball, a solid slider and changeup, and a fairly sound motion. I had no idea–and still have no idea–why Daniel Webb had such poor numbers to that point, but I knew the pitcher I was watching wasn’t far from being a very solid big leaguer. Lo and behold, Webb zoomed through the minor leagues basically from that point on and was getting big leaguers out effectively the following September.

You could call me a genius for predicting Webb’s rise from obscurity to being one of the top relief prospects in the game, but it doesn’t take genius to realize that a huge fastball, two solid offspeed pitches, and a reasonable idea of where the ball is going is a very solid package–one just has to be lucky enough to witness it.

Seeing as I had only started going to games in earnest the previous month, I wasn’t sure how frequently I should expect to witness anonymous prospects show off bigtime raw talent. As it turned out, I had a similar instance in 2013, but only one.

I first ran across Royals pitching prospect Aroni Nina on June 26. Like Webb, he was a 23-year-old in Low-A who had opened the season in the starting rotation, only to be yanked and pushed to the relief corps before the end of May. His career to that point was thoroughly unimpressive–he spent age 18-21 in the Dominican Summer League, put up a 5.85 ERA as a 22-year-old Rookie ball swingman in his US debut in 2013, and finally had made it to full-season in his sixth professional campaign. His 2013 ERA to that point was 4.65, and he had a 39/31 K/BB ratio in 50 1/3 innings. Batters were getting on base at a robust .371 clip off him.

Working as Lexington’s long reliever, Nina came in and worked three hitless innings, most of which I captured in this video:

You can see from that clip that Nina is a pretty interesting pitcher. He’s 6’4″, lanky, and projectable, he throws mostly 92-95 with some life from a fairly easy, low-effort motion, and he has a curveball and changeup with impressive life. There’s some wildness there, including one offering that would surely land a prime placement on Jeff Sullivan’s lists of wildest pitches if such things existed for minor leaguers, but the three-pitch mix and relative ease at which it’s delivered was intriguing.

That wasn’t the mindblowing moment, though–that came slightly over a month later, when I saw Nina face five batters in Kannapolis. In between the two outings, Nina had improved his statistics quite a bit–he had worked seventeen innings across five long relief outings, striking out seventeen, walking four, and allowing just five earned runs. I was interested to see him pitch again, but I never expected this:

That video might be the single most spectacular display of stuff I saw all year, and I saw plenty of pitchers with big stuff. A fastball at 92-97 mph with some life, a curveball with both power (79-81 mph) and absolutely¬†massive¬†tilt, and a solid changeup with good fade and speed separation. Forget intrigued; I was in awe, more than enough to forgive the fact that Nina doesn’t seem particularly interested in repeating his delivery in that video.

So, we’ve established that Aroni Nina has awesome raw stuff. But he still ended the year with pedestrian numbers, especially given that he was a 23-year-old reliever in Low-A. He pitched to a 4.19 ERA and a 77/45 K/BB in 86 innings,, with a strikeout rate of 20%–solid, but hardly reflective of the arsenal shown above. He did allow just two homers all year, good for a 3.70 FIP, but that’s still hardly outstanding.

But we also know that major league relief pitchers, even dominant ones, can come from all corners of the prospect map. Having big stuff of some kind is (usually) a prerequisite, but being effective at age 23 is optional. Or, at least, that’s the conventional wisdom, the sort of line we hear all the time when a John Axford or a Jonny Venters or, indeed, a Daniel Webb suddenly arrives on the scene. Relievers come from the strangest places, right?

So one might conclude that Nina’s raw stuff will trump the poor production and he’ll go on to be a lights-out reliever–the upside is there for that to happen. Or one might suggest that there are plenty of pitchers out there with big raw stuff who never make it, so he’s unlikely to as well.

There’s really just one way to resolve this debate: figuring out how often pitchers like this–guys with top-of-the-line raw stuff but persistent mediocre results–ultimately blossom into productive relief pitchers in the big leagues. Because we don’t have widespread pitch data for minor leaguers, it’s difficult to effectively quantify that, so instead, I’m going to look at it in the other direction: How many MLB relievers who a) have “big stuff” and b) are effective were still struggling at age 23?

In order to investigate this, we need to quantify both criteria. What is “big stuff” in an empirical sense, and what is effectiveness?

There are plenty of ways one can define these two terms, but I obviously had to settle on one. We have pitch data going back to 2002, so I exported a spreadsheet of all reliever seasons from 2002-2013 (min. 50 IP). To isolate “effective” pitchers, I found the mean and standard deviation of FIP for those seasons, and isolated the seasons that were more than one standard deviation above the average FIP, which turned out to be 2.93.

“Stuff” is a little more tricky to measure purely statistically. I settled on saying a pitcher had good raw stuff if he either:

a) had an average fastball velocity more than a standard deviation above the mean (which turned out to be 94.5 mph), or
b) had a fastball velocity that was at least average (91.6 mph) and used it less than average (63.2%), implying a solid collection of offspeed pitches.

There were 65 pitchers who put together at least one season in which they had the stuff and effectiveness to match the above criteria, with several posting multiple years. It’s not the biggest sample, but in investigating where each of these pitchers were at age 23*, we can shed some light on how many of these guys really are difficult to see coming.

*Note: For pitchers who were inactive or injured for most/all of their age-23 season, I used the next year they pitched in place of the age-23 season.

The first thing I did was to look at what level these hurlers played at. Somewhat surprisingly, a full 28 of them (43%) were in the majors for more than just a token appearance or two during their age-23 seasons. This included phenoms like Francisco Rodriguez, Huston Street, Craig Kimbrel, Jonathan Broxton, and Trevor Rosenthal, who were already tremendous MLB relievers at age 23, but it also included John Smoltz, Tom Gordon, and Kerry Wood, who were excellent starters who made late-career conversions. Oddly, Phil Hughes and Zack Greinke also were on the list, due to blip half-season relief stints early in their careers. Then there were others, like Ryan Webb, Juan Oviedo, Kevin Jepsen, Brett Cecil, and Kyle Farnsworth, who we don’t really remember as being especially effective at young ages, but nevertheless, they managed to make it up to the bigs in some degree by age 23, so they can hardly be said to come out of nowhere. Sure, Farnsworth had a 6.13 FIP as a 23-year-old starter in 1999, but he had a huge fastball and had a decent upper-minors track record as a starter at 22–developing into an above-average relief pitcher a couple of years later isn’t a huge step.

So let’s look at the rest of this group of 65–the other 37 hurlers. Fifteen of these spent their entire age-23 season, like Nina, without advancing to Double-A or higher. Another 14 spent their age-23 campaign entirely in the upper minors–Double-A, Triple-A, or both. The other eight spent time in both the lower and upper minors, rising throughout the year.

We can also break the pitchers in this group down by what role they were used in as 23-year-olds. In this case, twelve were relievers, twenty-one were starters, and four were in some sort of swing role.

Of course, age, level, and role don’t tell the whole story of how “out of nowhere” a pitcher is. If a 23-year-old Low-A reliever were to strike out 100 batters in 60 innings while walking four, he’d probably get noticed (and, frankly, promoted before he would reach the 60 inning mark, but that aside…). Conversely, there are plenty of 23-year-old upper-minors starting pitchers who get as little buzz as Nina does and aren’t considered legitimate contenders for future MLB jobs in any role.

It’s tough to draw a hard line between those who put up numbers worthy of notice in this group and those who did not, so in lieu of that, I want to point out some interesting statistical tidbits we can find in these cases.

I looked at strikeout rate, ERA, and FIP for the pitchers. The average strikeout rate was 22%, the average ERA was 3.83, and the average FIP was 3.55. Certainly, plenty of pitchers established themselves as very interesting at age 23 even without making the big leagues. Grant Balfour struck out 33% of the batters he faced as an upper-minors reliever. Jonathan Papelbon and Brad Lidge were extremely effective High-A starters. Brian Wilson had a 1.35 ERA across three levels. Tom Wilhelmsen and Jason Motte weren’t even pitching professionally at 23, but they took to it from the moment they next stepped on a pro mound.

However, thirteen of the 37 minor leaguers failed to crack the 20% strikeout rate mark, and only one of those–Jonny Venters–saw time at Triple-A in his age-23 season. Most of these pitchers were starters, with the two exceptions being Heath Bell and Steve Cishek; Fernando Rodney and Steve Delabar worked in swing roles, however. It’s hard to believe that Rodney, who now regularly posts strikeout rates in the upper 20s, struck out just 15.86% of opposing batters as a Low-A swingman at 23–in a lot of ways, he’s a better comparable for Nina than just about anyone on this list. Some other surprising names are on the sub-20-percent strikeout list, like Octavio Dotel, Matt Thornton, Jonny Venters, and Damaso Marte–players who were, for at least a brief period of time, intimidating bullpen presences who were capable of missing MLB bats or a regular basis. The lowest strikeout rate on the list was 11.4%, and it belonged to Alan Embree, then a Double-A starter; Embree would go on to strike out 20.8% of batters in his long career, including 32.3% in 2002.

Sixteen of the 37 pitchers had ERAs over 4.00, while eleven had FIPs that topped that mark, with the worst again being Delabar and Bell. Sergio Santos had an 8.16 ERA in his first season pitching, but his FIP was a more reasonable 4.11, he struck out over 20% of batters, and he was rushed through four levels in a scant 28 2/3 innings. Some new names that pop up are Joel Hanrahan (5.08 ERA, 4.93 FIP) and Ramon Ramirez (4.39, 4.20); Jean Machi (6.03 ERA, 3.88 FIP) was a victim of Cal League inflation that compounded his poor control (58 BB in 97 IP). Two pitchers that had ERAs over 4.00 while spending the entire season in Low-A, as Nina did, were Guillermo Mota (as a starter) and David Carpenter (as a reliever), though both had FIPs closer to 3.00.

This all paints an incomplete picture, but we can take a couple of things from it. First, despite the claim that relievers “emerge from nowhere,” a lot of dominant, intimidating relievers come from fairly obvious places. K-Rod, Street, Chapman, Broxton, Bobby Jenks, Kelvin Herrera, and others were well-established MLB relievers at very young ages. Others were effective starters who moved to the bullpen for other reasons, like Wood, Gordon, Smoltz, and Brett Myers. Others, like Trevor Rosenthal and Jake McGee, were touted starting prospects who switched to the bullpen out of organizational need (or organizational convenience, depending on who you ask) and quickly found a home. And still others remained in the minors at 23, but showed strong signs of an impending quick maturation to MLB effectiveness in some role, like Papelbon, Wilson, Lidge, and Balfour.

In fact, the overarching weirdness of the group seemed to stem not from many of the players rising out of statistical obscurity, but rather a select few coming from bizarre origins. Motte, Carpenter, Mota, Santos, and Carlos Marmol were all converted position players. Delabar was injured and retired shortly after his age-23 season. Wilhelmsen didn’t play organized baseball from age 19 to age 26. Joe Nathan went through a series of injuries as a starting pitcher, then suddenly emerged as a bullpen force.

Indeed, there wasn’t really anybody who had the profile of Nina or even the now proven-successful Webb. The only pitchers who worked in a relief role in Low-A and spent the whole year there were Carpenter, who had just converted to pitching, and partially Rodney. There weren’t any pitchers who didn’t even make it to full-season ball at 23, either. Given that we’re talking about a twelve-year span of dominant relievers, it’s somewhat striking that there are so few precedents in that regard. That doesn’t mean that it can’t be done, of course. As Webb shows, good stuff is good stuff, and it’ll get a reliever far if he has an idea what he’s doing with it.

Perhaps, then, our notion of the strangeness of reliever origins comes from two places: First, they can come from a number of places (converted position players, converted starters, or plain-old career relievers), and guys like Axford, Wilhelmsen, or Delabar can basically come off the street and immediately find success in the role if they can throw hard, have another pitch that moves, and throw both in the strike zone. Certainly, there are other types of effective relievers beyond the “pure stuff” types discussed here, too, like sidearmers and deception specialists–throw it all together, and nearly every team is bound to have a reliever or two who has some interesting quirk or narrative that feeds the notion of relievers springing from nowhere.

And the second thing, I think, is the same thing that made the afternoon of August 19, 2012 and the evening of July 30, 2013 so special for me–we never really think about relievers much. Most prospect talk largely eschews minor league relievers, and you’d be hard-pressed to find large portions of fanbases anxiously tracking the progress of their organization’s relief prospects. And when we take in a major league game, we start out focused on the starters, not really thinking about relievers, except for maybe the established closers of the teams that are playing. Relievers, especially middle relievers, don’t have anyone’s attention until they begin their jog in from the bullpen. And yet, unlike starters, they can pitch in a ton of games, and so they can seem virtually ubiquitous once they are trusted with high-leverage roles and start to gain a track record and some momentum.¬†And so they can go from seemingly nowhere to everywhere in the blink of an eye–even though the stuff was probably always there, or at least somewhat there, lurking just beyond our view.



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Nathaniel Stoltz is a prospect writer for FanGraphs. A resident of Bowie, MD and University of Maryland graduate student, he frequently views prospects in the Carolina and South Atlantic Leagues. He can be followed on Twitter at @stoltz_baseball.


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