Try to Tell the Difference Between Jake Arrieta and Tanner Roark

I have to admit to a bias. I’ve been aware of Tanner Roark since he entered the major leagues a few years ago, but my evaluation failed to evolve. In my head, Roark was still the guy he was when he made his first impression, as a strike-throwing and hittable sort who seemed to pitch with the intent of beating his peripherals. It is my job to try to know as much as I can, and I concede that this is my own failing, but in my partial defense, Roark hasn’t been close to the most interesting member of the Nationals’ pitching staff. Why would I choose to concentrate on Roark, when I could focus instead on Max Scherzer or Stephen Strasburg?

I have to admit to another bias. I find it tempting to believe that the larger population perceives things in the same way that I do. I haven’t kept up with Roark; therefore, I bet no one has kept up with Roark. Sometimes this gut feeling is correct. Sometimes, I’m just out of the loop. In any case, I’m about to put you all to the test. This isn’t going to be about me anymore.

The Cubs and Nationals are scheduled to begin Game 4 of their NLDS in a little while. It looks like some ugly weather could blow in, so maybe the game won’t be played, and maybe the starters will change. But for now, according to the lineups, Tanner Roark will start for the Nationals, and Jake Arrieta will start for the Cubs. Feels like an advantage for the Cubs, doesn’t it? Doesn’t it? Doesn’t it?

It can be hard to shake old impressions. Roark seemed to be mostly unremarkable. While that was happening, Arrieta was establishing himself as arguably the best starting pitcher on the planet. I think we all understand Arrieta’s now somewhat diminished, yet he was what he was, and that wasn’t so long ago. In an effort to be quicker to the point, I have prepared a 16-question quiz. Every question concerns 2017 statistics, put up as a starter. You are to select which pitcher you think put up the stat in question. Don’t worry if you get something wrong — there won’t be a follow-up. Getting something wrong is the whole point. You know how this works.

Arrieta is a 31-year-old righty who just made 30 starts. Roark is a 31-year-old righty who just made 30 starts. How well can you tell them apart, by their performances? Let’s see.

ERA

FIP

xFIP

wOBA against

K-BB% (HBP included)

GB%

HR/FB%

Hard-Hit%

Strike%

1st-Strike%

Contact%

O-Swing%

Fastball MPH

Three-pitch strikeouts

Four-pitch walks

Innings/Start

If you’re someone who actually made it all the way through the quiz, you’d probably like an answer key. How frustrating would it be to not know the answers? I’m not going to put the answers in this actual post, just because I don’t want to bias any voting, but here’s a link to a full table of numbers. The hyperlink provides a one-step barrier between the questions and the solutions. So, go ahead, click through, if you’re all done. There’s exactly one area where there’s a meaningful difference between the two pitchers. Granted, it’s an important area, but the stat itself is volatile, and Roark has excelled in that category in the past. Maybe I’m not reading the room correctly, I don’t know, but as I put this together, I couldn’t believe it. I couldn’t believe the similarities, because I’m guided by the perceptions that I have in my head, and my perceptions can sometimes be off.

I did figure that maybe Roark just faced worse competition. After all, the rest of the NL East this season was bad. But then, there are helpful numbers from Baseball Prospectus. Roark’s average opponent batted .253. Arrieta, .249. Roark’s average opponent had an OBP of .319. Arrieta, .320. Roark’s average opponent slugged .414. Arrieta, .416. Nothing there. Nothing…really…anywhere. If there’s a difference, it’s a difference in ceiling, but even that isn’t a thing that really exists in a knowable sense. Arrieta used to be as good as anyone else. Why should we care about that now, if the performance no longer matches up?

No need to go any further. I, at least, have learned something today. I didn’t expect to learn it, but then, that’s the fun of statistics.

We hoped you liked reading Try to Tell the Difference Between Jake Arrieta and Tanner Roark by Jeff Sullivan!

Please support FanGraphs by becoming a member. We publish thousands of articles a year, host multiple podcasts, and have an ever growing database of baseball stats.

FanGraphs does not have a paywall. With your membership, we can continue to offer the content you've come to rely on and add to our unique baseball coverage.

Support FanGraphs




Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

newest oldest most voted
carter
Member
carter

Baseball reference likes one of the players much, much better.

swingofthings
Member
swingofthings

That comes down to runs allowed, which is captured by the ERA in this article. But is there any reason to believe, from this moment on, that will continue? Nothing in the stats, at least.

Skin Blues
Member
Member
Skin Blues

If you look at their entire careers rather than just the previous 6 months, yes, there’s a reason to believe Arrieta will continue to post a much better ERA.

Stump Wiedman
Member
Stump Wiedman

Last question of the quiz. Which career ERA belongs to which pitcher? Pitcher A:3.57; Pitcher B:3.41.

sadtrombone
Member
sadtrombone

Yeah, but who cares what they think?

(I was going to post a longer comment but that was gonna be the main takeaway either way)

bly
Member
bly

The FG projection agrees with this. The series win %s started at 50/50 suggesting the batting is projected to be about the same. That remains true for today’s series projections with the Nats being given a 25% chance of winning. But today’s game, with Roark in as the starter, has Cubs 59%, Nats 41% chance of winning.

Actually, as of right now, on the score page, Roark is starting and Strasburg is batting 9th. I assume we’ll get new projections once that is fixed. But, they won’t be relevant to this article.