clock menu more-arrow no yes mobile

Filed under:

Casey Janssen: Two Pitchers for the Price of One

Casey Janssen has been a really good pitcher for quite some time now. Even better, he's good in a really interesting way.

Kevin C. Cox

In an undeniably disappointing year for Toronto Blue Jays fans, Casey Janssen has been one of very few players to exceed expectations. Janssen has been 11-11 in save opportunities while sporting an excellent 2.25 ERA to go along with a 2.06 FIP and a 0.6 WAR that ties Brett Cecil (who would have possibly guessed that?) for the Blue Jays lead among pitchers. The fact that two relievers lead the Jays pitching staff in WAR is a sad, sad, story for another today. Today I would prefer to look at the uplifting story of Casey Janssen. Janssen is playing through some troubling shoulder troubles and it has taken its toll on his velocity (his fastball has dropped to an average of 89.9 mph this year after sitting at 91.7 last year and 92.1 in 2011), yet he has remained as effective as ever. How is Janssen thriving as the virtually unheard of soft-tossing closer? The answer is that Casey Janssen has unbeknownst to the general public decided that he will actually be two pitchers.

Of course Casey Janssen is not literally two humans, although that would probably make for a more interesting article. What Janssen has done is develop two completely different pitching styles, one for facing left-handers and one for facing right-handers. Against lefties Janssen is playing the role of a Brandon Webb type groundballer whereas against righties he's a Yu Darvish-esque strikeout machine. Those comparisons are hyperboles of course, but they give you an idea of what's going on here. Janssen is a Dr. Jekyll and Mr. Hyde with no Mr. Hyde. He's more like Dr. Jekyll and very different but actually slightly better Dr. Jekyll. A pitcher having platoon splits is nothing new but Janssen's are extraordinary because they both reversed (i.e. he is more effective against left handed batters) and demonstrate such a stylistic difference. To demonstrate this point, I made up three charts to show some of Casey Janssen's splits since 2011. I took data since 2011 because this year's 16 innings pitched is a laughably small sample (the sample for 2011-2013 is 135.1 innings) and it is also the time period in which he has become a truly dominant reliever. The first chart shows some overall numbers to give you an idea of what Janssen has done against both RHB's and LHB's since 2011:





BA Against

OBP Against

SLG Against





















Your first impression upon seeing these numbers is likely be to be impressed with Janssen's ability to shut down lefties. He's no slouch against same handed batters but there is quite a difference. It should be noted that some of the difference could be mitigated by normalizing the HR/FB rate across LHB and RHB. When facing Casey Janssen left-handers are hitting homeruns on 2.8% of their flyballs whereas right-handers are putting it over the fence 12.9% of time. That difference could be something meaningful, but most likely it is just noise. Given that we are talking about 10 total homeruns here I don't think I can confidently say anything intelligent about it. I'm just giving you the numbers in the interest of full disclosure.

What I'm more interested in than differences in effectiveness is differences in style. The following two charts show how Casey's approach changes depending on the handedness of his opponent. The first is his strikeouts and walks:













The numbers against lefties aren't shabby but that 6.4 K/BB against right handed batters is something else. Janssen shows the ability to completely blow away righties with the strikeout whereas his K% against left-handers is just above league average. His BB% does not show much of a split, which is not particularly surprising given his excellent command.

The chart below show Janssen's splits when it comes to batted balls:



Flyball %










Casey just doesn't let left-handers get the ball in the air. This helps account for the fact he has only given up two home runs against them since 2011. Against RHB Janssen allows quite a few flyballs and is below average when it comes to keeping the ball on the ground.

The most obvious assumption here is that these differences are related to pitch usage. One would think that Casey is just pounding LHB's with sinkers and not using them against RHB. The interesting thing is that this isn't really the case. 2012 is the only year in which Janssen was throwing noticeably more sinkers to LHB (10% to 3%). In 2011 he threw 12% sinkers against both LHB and RHB and this year he essential scrapped the pitch throwing it only 1% of the time according to Brooks Baseball.

I'm not exactly sure what the takeaway is here. Janssen seems to have two completely pitching approaches in his bag of tricks and that probably has something to do with his success. A lot of pitchers claim that they pitch their game regardless of the batter, but those pitchers probably aren't as successful as Casey Janssen. Casey Janssen is paying attention to who he is facing, pitching based on his opponent, and doing so in a dominant manner. If you are going to hover around 90 mph with your fastball and you want to close in the big leagues you have to be doing something different. It seems like Casey Janssen is.