Madison Bumgarner and His Strikeouts

Madison Bumgarner has pitched like a top tier starter since he appeared on a big league mound in 2009. While his strikeout rate—8.46 career K/9—has always been above average, something has clicked with the big lefty this season, launching him into legitimate No. 1 starter territory. Through 13 starts this season, Bumgarner has a K/9 of 10.04, ranking third in the NL behind only Stephen Strasburg and Zack Greinke.

What’s most fascinating about Bumgarner is that he’s dominating hitters basically with two pitches, both of which—the fourseamer and the cutter—are high velocity pitches. PITCHf/x has Bumgarner throwing a fourseamer 41.19% of the time and a cutter—which FanGraphs lists as a slider—37.22% of the time. For the sake of simplicity, I will refer to the latter pitch as a cutter.

This season, the fourseamer has been especially effective for Bumgarner. Batters are swinging at the pitch at a higher rate (45%) than any previous season, and they are making contact with less frequency, as the 29.50% whiffs per swing shows. In 2013 batters whiffed at the pitch 26.69% of the time when swinging; between 2009-2012, the rate was never higher than 19.81%.

The cutter, of which the usage rate has dropped almost 2% since 2012, has seen similar results as the fourseamer. Hitters swing at the cutter 57.25% of the time and whiff with 24.33% of those swings.

A big reason for the diminished contact rate is the fact that Bumgarner is throwing his pitches in strike zone less often than in years past. His in-zone rate is just 39.63%, the only time in his career that it’s been under 40%. When hitters swing at pitches out of the strike zone—which they do 36.01% of the time, a career high—they whiff 37.7% of the time. When swinging at pitches in the zone, the whiff rate is 16.75—a rate that surpasses those in any of his previous seasons.

When Bumgarner gets hitters into two-strike counts, his approach stays the same for the most part. In those counts, he throws his fourseamer 41.41% of the time and his cutter 37.5% of the time, both numbers just slightly above the overall usage in any count. The one aspect that changes in two-strike counts is Bumgarner’s usage of his curveball. Overall, he throws the pitch 11.93% of the time. In two-strike counts, the usage rate jumps up to 17.5% and batters swing at it 55.84% of the time. The result is a 20.78% whiff rate, highest of all Bumgarners pitches in two-strike counts (16.23% fourseamer, 14.55% cutter).

Another aspect of Bumgarner’s dominance this year has been his ability to fight back and limit damage when behind in the count. His fourseamer and cutter have been the main reason for this. When behind in the count 1-0, Bumgarner has thrown the cutter 43.57% of the time and the fourseamer 35.71%. Here’s what happens with those pitches in 1-0 counts:

Pitch Type	Whiff/Swing	Foul/Swing	Swing%
Fourseamer	33.33	50.00	36.00
Cutter	16.67	53.33	49.18

 

Between the two pitches, over half of the swings result in a foul ball. Add in the whiff rates and Bumgarner finds himself back in the drivers seat more often than not after falling behind.

What about the 1-0 counts that get to 2-0? More often than not—62.22% of the time—he throws the cutter while throwing the fourseamer 31.11% of the time. Here are the results:

Pitch Type	Whiff/Swing	Foul/Swing	Swing%
Fourseamer	33.33	50.0	50.0
Cutter	16.67	53.33	67.86

 

Again, more often than not, Bumgarner is able to fight through being in an unfavorable count. Once he gets to 2-1, he continues to attack hitters with the fourseamer (35.71%) and the cutter (54.29%). Here’s what happens:

Pitch Type	Whiff/Swing	Foul/Swing	Swing%
Fourseamer	33.33	50.0	84.0
Cutter	16.67	53.33	73.68

 

In addition to these numbers, Bumgarner’s current walk rate of 2.01 BB/9 further shows that he doesn’t often lose hitters when falling behind. Rather, he uses his fourseamer and cutter to get himself back into a favorable count and is thus putting hitters away at a career-high rate.