Through just two and half seasons, Madison Bumgarner has already accumulated 11.0 WAR, which is an even more impressive number when you consider that this is just his age-22 season. Bumgarner has followed a breakout 2011 campaign with a season of similar quality, with an increased strikeout rate and decreased walk rate despite a rather large uptick in home runs allowed. Even with the increased home run total – 20 allowed this season compared to 25 in his previous 325.2 innings pitched – he has gotten away from the “hittable” label and has seen his BABIP drop to .265, putting his career mark at a standard .299 mark compared to the rather high .317 prior to this season.
One of Bumgarner’s biggest assets, much like Chris Sale who I covered last week, is an incredibly deceptive delivery. This shouldn’t be news to anyone who has seen him pitch, and if you are reading this post than I imagine there’s a rather high chance you have. But even so, the low arm slot and off-center delivery makes Bumgarner hell on left-handers, as just nine of the 166 lefties he has faced have recorded an extra base hit, putting his wOBA against at a miniscule .249. Teams are rather aware of his dominance against lefties, which is why he has been allowed to face just 166 of them compared to the 593 righties that have stepped up to the plate against the tough lefty. What makes Bumgarner even more impressive is that his delivery has not significantly diminished his value against right-handers either. While he has the delivery similar to Sean Burnett – a dominant reliever with a .326 wOBA against righties – he has still performed quite well against righties this season, and has continually improved against them throughout his career. His wOBA against righties each of the past three seasons is .327, .296, .284.
The main difference between Bugmarner against righties this year and in the past is an increased reliance on his slider – 37% frequency usage against 25% for his career before this year . Last year he threw the pitch roughly 30% of the time, so the increased usage of his slider has correlated with better overall performances against righties throughout his career. There is likely a limit that he is not too far away from that could eventually cause him to receive worse results against hitters of opposite handedness, but he has not tested that level quite yet.
Conventionally the slider would be a pitch that righties should handle decently considering his arm slot and delivery, but what Madison has done a very nice job of is working the back door slider. While he most frequently throws the pitch down and in to righties, he receives a majority of his called strikes against righties on the outer half. His incredible ability to locate the pitch, which is evident by his 72.9% strike right with sliders to right-handed hitters, is one of the main reasons for his success with the pitch. In addition to incredible command of the pitch, he has the sixth highest slider velocity according to PITCHf/x and only David Price has a higher slider velocity of any other left-handed pitcher.
If there is one pitch that is most responsible for Bumgarner developing so rapidly into a top tier starting pitcher, it’s the slider. It will certainly be interesting to see how the Giants continue to push the envelope with the pitch in terms of overall usage. As Eno Sarris wrote last year, pitchers who throw the pitch more than 40% of the time more often succumb to major surgery or injury to their arm than others, so the Giants may opt to keep him at a level close to where he currently sits. A player with such a low walk rate and such a high rate of breaking balls is certainly rare, so it becomes easy to appreciate what Bumgarner has been able to do in his first few years in the majors. He was my pre-season pick for Cy Young and while he fell short of that distinction, he certainly has not disappointed and if he commands his slider as he has this season I see no reason why he will any time soon.