Kenley Jansen’s Dominant Fastball

Every year it seems we hear about a former position player trying to transition to the mound in order to save his professional career.

Two years ago, it was Tony Pena Jr. with the Royals who moved from a light-hitting shortstop to reliever. In 2010, Sergio Santos of the Chicago White Sox grabbed headlines after making the big leagues as a shutdown reliever after struggling for a better part of a decade as a shortstop. Trevor Hoffman also failed as a shortstop before trying his luck as a pitcher. Carlos Marmol played two years as a catcher and outfielder for the Cubs before stepping foot on the mound for good.

It’s not uncommon. One can set foot in a big league bullpen and likely find a former position player lurking in that group — a player that just couldn’t cut it as a professional ballplayer at their respective positions — but the organization saw a special arm they wanted an opportunity to refine on the mound.

In 2011, the position-player-turned-reliever that firmly burst onto the scene was right-hander Kenley Jansen of the Los Angeles Dodgers.

The native of Curacao started as a 17-year-old catcher in the Dodgers’ farm system. He hit .292/.331/.425 in his first professional season, but his numbers dropped significantly in subsequent years. In the end, his career .229 average and .647 OPS simply weren’t good enough, and Jansen faced the prospects of becoming an A-ball journeyman with no more big league dreams.

Then, the Dodgers handed him a baseball, told him to step on the mound, and realized they hit the jackpot when he started to throw 93-94 MPH fastballs past almost every opposing hitter in the minors. Jansen rocketed through the minor league system in only two years — struggling with command at times as he learned the intricacies of being a professional pitcher, but that’s to be expected from a guy who had never pitched before halfway through the ’09 season.

Fast forward to this past year. Kenley Jansen enjoyed his second cup of coffee with the big league club — though technically his true rookie season — and did nothing but break the single-season strikeout rate record. He struck out 16.1 batters per nine innings, and that is the highest strikeout rate in baseball history amongst pitchers with at least 40 innings pitched in a season.

While that is an amazing accomplishment in itself for a rookie reliever, it’s even more noteworthy when one realizes just how it was done. The former record holder, Carlos Marmol, gets a myriad of hitters to swing-and-miss on the strength of his wicked slider; a slider is a swing-and-miss pitch. That makes sense. Eric Gagne (third-best single-season strikeout rate) struck out a ton of batters with a plus-plus changeup. Another swing-and-miss pitch.

Kenley Jansen struck out 16.1 batters per nine innings almost exclusively with his fastball. He threw it 86.8% of the time, and only five relievers in the league had a better fastball, according to the wFB rankings.

Throwing the fastball that exclusively can lead to problems on the mound. The opposing hitter knows what pitch is coming, and big league hitters can turn on any fastball if they can sit dead-red at the plate.

Except Jansen’s fastball, apparently.

The 24-year-old not only threw approximately 87% fastballs in 2011, but he also filled up the strike zone. Only relievers Matt Belisle, Octavio Dotel, and Matt Capps threw more pitches inside the zone than Jansen. So opposing hitters knew which pitch he was going to throw and knew that it would more than likely be within the strike zone, but opposing hitters still struck out 44% of the time.

Turns out opposing hitters simply cannot make contact with his fastball. Of qualifying relievers, only Craig Kimbrel posted a lower contact rate (63.4%) than Jansen (63.5%) — and Kimbrel accumulated those numbers through the use of his phenomenal slider, which he threw 30.5% of the time.

Jansen routinely sits 93-94 MPH with his fastball, but can dial it up to 95-97 MPH with regularity. The pitch explodes on hitters and even has some ride to it as it reaches the strike zone. It’s a straight-up nasty pitch that will only improve in effectiveness as he continues to learn how to be a pitcher and further develops his slider — which is a true, two-plane slider, but lacks consistency.

It’s incredible to that just three seasons ago, Jansen was a little-known catching prospect who was hitting .198/.256/.276 in the California League and was faced with the decision of whether he wanted to transition to a relief pitcher or be released from the Dodgers organization.

Now, despite the fact that Javy Guerra will likely begin the season as the Dodgers’ closer in 2012, the most dominating reliever in Los Angeles before the year is over will probably be Kenley Jansen.




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J.P. Breen is a graduate student at the University of Chicago. For analysis on the Brewers and fantasy baseball, you can follow him on Twitter (@JP_Breen).


33 Responses to “Kenley Jansen’s Dominant Fastball”

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  1. William says:

    Now this is a cool story bro.

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  2. wiggly says:

    Interesting story. I wonder if you could get PitchFX data or something to see if he’s just super good at staying out over the corners, if there’s some really unusual action, or what. Interesting- thanks!

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  3. test says:

    It’s a straight-up nasty pitch that will only improve in effectiveness as he continues to learn how to be a pitcher and further develops his slider

    I’ll take that bet – I don’t think his fastball will ever be that effective again, because he just set an alltime record. Guys who set all time records don’t generally continue to improve. He could have a hell of a good career and never approach 2011 numbers again.

    Or maybe he is the new Rivera? One pitch, in the zone, can’t hit it. Sounds familiar, and like a good reason not to mess with it until required.

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    • SKob says:

      He set an all time record in what was officially his rookie season. Yeah! I’m sure he’s peaked! Good bet! I would avoid Vegas if I where you!

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      • I am not saying that Jansen will definitely never do this again.

        BUT, everyone recognizes the volatility of relievers, and how guys can go from amazing to not-so-amazing real quick. Halfway through this season, the Tigers’ Al Alburquerque was the one on pace to set the K/9 record. Then he suddenly fell off pace. It happens for relievers.

        If Jansen could somehow sustain this for many years, he would be among the best relievers of all time. No one should be ready to be that committed to Jansen yet.

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      • Bip says:

        Considering that for a reliever, having a pitch that the rest of the league isn’t used to seeing is an advantage, and they learn how to hit it better as they see it more, yes, it is likely that it’s effectiveness has peaked. Usually all time records require everything to go right— the pitcher has to have a unique combination of effectiveness, advantages they don’t control, and luck to do it— so one shouldn’t say that it’s likely a pitcher will repeat a record breaking performance.

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    • exxrox says:

      I agree here and think that SKob is delusional – if you think the man can IMPROVE on his >16 strikeout rate, try again. Yes he will have more experience as a pitcher, but the league will also have more of a report on his stuff and movement. It is so incredibly unlikely that he repeats this season (and I am avoiding the word fluke) that I would certainly go to Vegas with it.

      I generally advise against betting in favour of ALL TIME records. Do you also think that Matt Kemp will go 50/50 next year, because he is still improving?

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  4. Scott says:

    His fastball is a cutter that’s very close to Mariano’s in terms of movement, but he throws it in the mid-90s.

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    • Bryz says:

      I don’t think it’s a cutter. Pitchers that throw over the top and very hard tend to have very straight fastballs. I think that while PitchF/X may call it a cutter, I think it’s more likely that it’s just a straight-as-an-arrow fastball. A straight-as-an-arrow fastball that apparently no one can hit.

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      • wily mo says:

        uh well i suppose that kind of pitcher does tend to do that but if this particular dude is throwing the fastball 90% of the time and it’s in the zone and he still set the all-time K9 record i’m going to suggest the possibility that his fastball is unusual in some way

        i know it sounds crazy

        there must be a way to find out. has anybody seen video of this guy. are the dodgers on TV

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      • Paul says:

        But he doesn’t throw over the top. Look at his release point at TexasLeaguers Pitch F/X. It’s virtually identical to Mariano’s.

        Isn’t it pretty widely recognized and discussed by Kenley himself that it’s a cutter?

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      • Table says:

        As a Dodger fan, I can tell you, it’s not a straight fastball. It looks like a cutter, and he calls it a cutter.

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      • Greg says:

        The term cutter is often a term of art. Mariano Rivera’s “cutter” is really a four-seam fastball with late movement that sinks and darts away from a righthanded batter. No one taught him the grip and said, “This is a cutter.” It’s a pitch that Rivera discovered organically. Rivera did not set out to throw a cutter. He simply was fooling around with different grips, which pitchers do all the time, and just throwing a good ol’ fashioned four-seam fastball. He discovered that when he threw his four-seamer with a slightly off-centered grip, it had nasty late movement. Hence, the “cutter” was born, although Rivera didn’t call it a cutter at the time.

        The same sort of thing happened with Kenley. His “cutter” is his two-seam fastball. He discovered that his natural two-seamer had cutter like action. Again, it was an organic discovery, not something he intended to accomplish.

        The reality is that pitchers have been throwing cutters for a long, long time. We just didn’t call them cutters. They were fastballs with late, slider-like movement. And some pitchers are just more blessed than others with having more natural movement on their fastballs, which is why everyone who throws a cutter doesn’t have the same success with the pitch as Mariano Rivera or Roy Halladay.

        What sets Rivera apart from virtually any other pitcher not named Halladay is his utter command of the cutter. And that utter command is due to Rivera’s ability to repeat the same fluid mechanical motion over and over again. Kenley Jansen has not been able to do that in his very brief career as a pitcher. Unlike Rivera, Jansen’s mechanics break down far too often.

        Unless Jansen can become more consistent with his mechanics, I suspect he will have a very brief career. He has sufficient velocity and movement to live off of his “cutter” as a short reliever. But unless he develops better command and reduces his risk of injury, his career will probably be similar to Joel Zumaya’s.

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    • Greg says:

      Throughout most of his career, Rivera’s “cutter” consistently traveled 94 to 96 mph. Watch a tape of him in the memorable 7th game in the 2003 ALCS against Boston (the Aaron Boone game). He threw three innings, and his cutter consistently was hitting 95 mph on the radar gun. The dude was nasty.

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      • Craig says:

        I think it would be very odd if Kenley through a two seam fastball that tailed away from right handed hitters. A two seamer from a righty will generally til in towards right handed batters whereas a “cutter” is pretty much any high velocity pitch that breaks in towards a left handed hitters hand from a right handed pitcher.

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      • Bob says:

        To craig: to throw a two seamer a pitcher places his fingers along the seams of the ball, not across them. In order to make the ball move in to a RHB, from a RHP, a pitcher moves his fingers to the right of the seams. This causes more pronation as you release the pitch, which “turns the ball over” and makes it sink. By doing the opposite, or moving your fingers to the left of the seams, it causes your hand to stay on the side of the ball, releasing it with almost spiral spin. This results in a two seamer that cuts in to a lefty.

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      • Craig says:

        To Bob: Not sure why that comment would be to me. That is basically what I said. Cutters move away from RHB. It may still be a 2-seam fastball, which is why I put cutter in quotes. My comment still applies. It can be the same pitch but just has a different title.

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  5. The Dude Abides says:

    His cut fastball is virtually unhittable. He makes really good hitters (from both sides of the plate) take terrible swings, even freezing them when they already know the pitch is coming. It actually sits at 94-96, sometimes dialing up to 98. And the slider has a huge break and is usually 82-85.

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  6. Brad Johnson says:

    Not to ruin my own deep sleepers, but I’m told Shawn Tolleson has the stuff to be the best reliever in Dodgerland.

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  7. Ivdown says:

    I don’t know how he does it, but he just has the amazing ability to shut the door. I believe it was Kershaw’s last 2 starts, he got into trouble in the 8th inning putting 2 runners on both times with 1 out, and Kenley came in and there was absolutely no shot because he blazed the fastball by them. They were great moments.

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    • Bip says:

      I was at the game for the best one of those, the one against the Giants. Kershaw started the eighth inning, got one out, but allowed I think two baserunners, so Mattingly pulled him and brought in Jansen. Jansen struck out Carlos Beltran and Pablo Sandoval on 7 pitches to end the inning. The best part of that was that it was for Kershaw’s 20th win, and that Jansen was Kershaw’s catcher for some of the time he was in the minors.

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      • Ivdown says:

        That inning was absolutely nerve wrecking. Besides in the playoffs game 2 NLDS against the Cards, I’ve never ever been more nervous at a game.

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  8. Anon says:

    Catcher turned reliever with a good fastball? Motte.

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  9. Regarding Jansen and Mo, a much more apt comparison would be David Robertson:

    Velocity
    Rivera: 91.8
    Robertson: 92.5
    Jansen: 93.7

    Horizontal spin deflection
    Rivera: +2.7
    Robertson: +0.4
    Jansen: +0.5

    Vertical spin deflection
    Rivera: +7.0
    Robertson: +10.5
    Jansen: +10.6

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    • BTW, in an attempt to strip out biases, I took those values for a) road games only and b) pitches with the Gameday ID “cutter” for Rivera but “cutter” or “four-seam fastball” for Robertson and Jansen (MLBAM uses both tags for those pitches).

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  10. bill says:

    Apparently Jansen is a lefthander. Throwing a baseball is the only thing he does with his right hand. It may seem far-fetched but this may be a factor in his delivery that causes his fastball to behave in a particularly unique way.

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    • bill says:

      You know what, no.That’s garbage. I pulled up some video of him pitching. Its the spitting image of Mariano Rivera. The ball has a little less sink but more velocity. Same easy delivery, straight-arm motion, long stride – everything. Its simply a superior cut fastball.

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  11. YazInLeft8 says:

    Great article. I don’t know a lot about hitters switching to pitchers, but could he possibly attribute this nasty fastball to his catching somehow?

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