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Wandy's Ability to Control Left Hand Batters: Let's Slice the Numbers

The folks at fangraphs are having some fun writing about players' lefty/righty splits.  And I can't blame them; it's an intriguing subject, and now fangraphs' data is replete with fine split stats by season for each player.  Dave Cameron at Fangraphs raised a subject which prompted me to examine Wandy Rodriguez's split stats for so-called "luck" statistics.

Cameron was drawn to Jered Weaver's splits and his seeming ability to repress BABIP and HR/Fly stats against same side hitters.  Since these two stats are widely viewed as mostly outside the pitcher's control, showing that pitchers may exert some control over batted ball and HR-flyball ratios would be a noteworthy finding.  He mentions some speculation that Weaver's arm slot and resulting effect on RHBs may be the cause.  He then picks out some pitchers with similar arm angles who also exhibit some above average ability to repress BABIP and HR/Fly ratios against same side hitters.  Cameron doesn't claim that this proves anything, but throws the idea out there for discussion.

Given the prompting of Cameron's article, it may be worthwhile to examine Wandy Rodriguez's splits. Wandy has turned into a top 10 lefthanded starting pitcher in the National League.  Wandy's velocity is in the 90/91 range, and he also exhibits an excellent curveball and a plus change up.  Given that Wandy doesn't light the radar gun up with mid-90's heat, his success is widely attributed to a good deal of deception in his delivery.  His fastball is sometimes called sneaky fast, and hitters seem to have trouble immediately picking it up. 

I'll look at both career splits, and splits over the last three years.  During Wandy's 5 year career, he made some apparent changes in the last three seasons which could factor into his improving performance.  After 2005 and 2006, Wandy virtually ditched his slider and cutter, and increased his use of the curveball.  He also reduced his use of the change up slightly.  Over his career, Wandy has shown a clear platoon split with a FIP of 3.86 vs. LHB and 4.28 vs. RHB. However, that split is much more pronounced in the last three years.  In 2005-6, Wandy didn't not exhibit a noticeable FIP split vs. LHB.  However, in the last three years, the average FIP advantage over LHB was 0.8 runs.  Over the last three years, Wandy's K/9 for LHB is 9.27 compared to 8.02 for RHB.  The K rate split isn't significant during the first two years.

Now, let's move to the luck stats and their splits.  For BABIP the average platoon split difference for lefthand pitchers is 5 points, according to Cameron's data.  Wandy's career platoon split advantage over LHBs is 7 points (.311 vs. .304), which is higher than average but not by a lot.   Over the last three years, Wandy has exhibited an average BABIP differential of 54 points (.286 vs. LHP and .341 vs. RHP).  Given the reduced sample using only three years, and the fact that the platoon difference is really limited to the last two years, it's hard to say whether this is randomness or an indication of Wandy's ability to repress LHB's BABIP in recent years.

Cameron's data shows that LHPs have no real platoon differential for HR/Fly.  Over his career, Wandy's average HR/fly ratio is exactly the same (11%) against both LHB and RHB.  Wandy's HR/Fly ratio improved over the last three years (averaging about 9.7 %), but the average platoon advantage is slight (9.5% vs. 9.8%).  Indeed, looking at the erratic pattern, I don't see much basis for suggesting that Wandy has more control over flyballs going out of the park based on platoon splits.

Moving away from the platoon split issue, Wandy does show a significantly greater ability to control HR/flyball rate at home.  His career HR/fly rate at home (9.6%) is substantially below the away rate (.12.6%). And the home advantage is consistent from year to year.  One can speculate that Wandy has found a way to pitch to the big parts of Minute Maid Park.  Somehow Wandy has found a way, or perhaps a location, to keep RHBs from launching the flyballs into the Crawford Boxes at an excessive rate.

I don't have any definitive conclusions, except that Wandy is tough on LHBs and his run prevention versus LHBs has grown over the last three years.  The possibility exists that Wandy has developed the ability in recent years to reduce BABIP rates from LHBs, but that is somewhat speculative.  It doesn't appear that Wandy's has a significant ability to control HR/Fly rates versus one side or the other.  And Wandy's seems to use Minute Maid Park to his advantage, in terms of keeping flyballs inside the park.