The pitch mix of starting pitchers can be a driving force in skill changes from one season to the next.
To analyze the SP who have varied their pitch mix the most, we added together the pitch usage variances (using absolute values) from 2013 to 2014 across all pitch types based on PITCHf/x data.
We found that 31 guys have changed their pitch mix by at least 30% so far this season.
Here are the SP with the most extreme pitch mix changes from 2013 to 2014, along with their BPV variance over the same period:
Pitch Mix Changes - 2013 vs. 2014 YTD* ----2013 vs. 2014 YTD--- Name League BPV Diff Pitch Mix Diff ================== ====== ======== ============== Cashner, Andrew NL + 6 62% Hammel, Jason NL +56 60% Richards, Garrett AL +33 51% Sabathia, C.C. AL +60 49% Kluber, Corey AL +39 49% Burnett, A.J. NL -78 48% Erlin, Robbie NL +24 47% McAllister, Zach AL +25 47% Kennedy, Ian NL +83 44% Milone, Tommy AL -47 43% McCarthy, Brandon NL +60 43% Hughes, Phil AL +41 42% Ross, Tyson NL -26 41% Miley, Wade NL + 1 41% Archer, Chris AL -16 40% Feldman, Scott AL -25 39% Buehrle, Mark AL -36 39% Kazmir, Scott AL + 7 38% Shields, James AL +40 37% Peavy, Jake AL -65 37% Keuchel, Dallas AL +48 36% Wilson, C.J. AL +42 36% Lester, Jon AL +65 35% Perez, Martin AL -11 35% Jimenez, Ubaldo AL -39 35% Oberholtzer, Brett AL + 8 35% Kuroda, Hiroki AL +17 32% Samardzija, Jeff NL -11 32% Porcello, Rick AL -10 32% Wacha, Michael NL +62 31% Darvish, Yu AL - 5 31% *min 30 IP in 2013, 2014 YTD
These SP have seen an average change in their BPV from 2013 to 2014 of +11.
Here is a closer look at a bunch of guys in each league whose refined pitch mixes can help to explain their skill changes from 2013 to 2014.
AMERICAN LEAGUE
Yu Darvish (RHP, TEX) is throwing his slider 10% less often in 2014. In its place, he is throwing his 93-mph fastball more. It's a change in pitch mix that hopefully will reduce the stress on his arm. It has not caused significant deterioration in his skills. After an elite 140 BPV in 2013, Darvish has remained elite so far in 2014: 10.8 Dom, 2.7 Ctl, 35% GB%, 135 BPV. The only concern with his new pitch mix is his increased risk of gopheritis, since he allows more hard contact and flyballs against his four-seam fastball than his slider.
Phil Hughes (RHP, MIN) has been more dominant so far in 2014 than you might realize. He has a nifty 40/6 K/BB in 47 IP, good for these skills: 7.6 Dom, 1.1 Ctl, 32% GB%, 116 BPV. He has swapped his slider for more four-seam fastballs and cutters. His four-seam fastball has generated a high 11% SwK%, the highest swinging strike rate against that pitch at anytime in his career. Now's the time to ditch your previous frustrations with Hughes and get on board.
Dallas Keuchel (LHP, HOU) showed signs of something good late in 2013 due to some strong off-speed stuff, especially a dominant slider. He has increased the use of his secondary offerings even more in 2014. His four-seam fastball utilization has dropped from 27% to 15%. His two-seam fastballs are up from 29% to 40%. It's the pitch that is responsible for him having the highest groundball rate (65% GB%) in MLB. He has an amazing 81% GB% on his two-seam fastball. His slider (24% SwK%) and changeup (17% SwK%) give him two legit strikeout pitches. No reason to sell high here.
Corey Kluber (RHP, CLE) had a mediocre 4.14 ERA and ugly 1.51 WHIP in April, causing some owners to cut bait. We hope you didn't follow suit. He has been one of the game's most dominant pitchers so far in May: 12.9 Dom, 1.2 Ctl, 47% GB%, 223 BPV. He has also tweaked his pitch mix from 2013 to 2014. He has ditched his four-seam fastball for a sinker. So far, batters have a .959 OPS against his sinker, and he has generated a low 5% SwK% against that pitch. The reason for his success can be found in three dominant off-speed pitches: slider (21% SwK%), curveball (17% SwK%), changeup (18% SwK%). If Kluber can refine his sinker or go back to using his four-seam fastball more, he could become even better.
Jon Lester (LHP, BOS) is flashing the best skills of his career so far this season: 10.8 Dom, 2.4 Ctl, 37% GB%, 146 BPV. He is using his sinker less and cutter more. It has proven to be a smart move. Batters have mashed his sinker to the tune of a 1.056 OPS. His cutter has become a weapon. Hitters have a low .505 OPS against it, and Lester has produced a 14% SwK% with that pitch. Lester's quick start comes with nearly full skill support.
Garrett Richards (RHP, LAA) has made some significant gains in 2014, and the reason for them can be partially found in his pitch mix. He is throwing two-seam fastballs 30% of the time in 2014 compared to just 7% of the time in 2013. It's a pitch that has limited batters to a .656 OPS and has induced groundballs at an elite 68% rate.
NATIONAL LEAGUE
Andrew Cashner (RHP, SD) has changed his pitch mix more than any other SP so far in 2014. He is throwing fewer four-seam fastballs and a lot more two-seam fastballs. Batters have managed a low .542 OPS against his two-seam fastball. In addition, his slider and changeup have emerged as legit swing-and-miss pitches. The SwK% on his slider has jumped from 14% to 16%, and the SwK% on his changeup has increased from 10% to 18%. If his elbow is sound, Cashner's early dominance with his changeup—combined with his mid-90s heat—gives him a unique combo.
Jason Hammel (RHP, CHC) has enjoyed an early surge in his skills. After posting an ugly 46 BPV in 2013, his skills have improved across-the-board: 7.3 Dom, 2.0 Ctl, 44% GB%, 98 BPV. A change in his pitch mix could explain why. He threw his four-seam fastball 30% of the time in 2013. He's throwing it only 10% of the time now. He uses his two-seam fastball 50% of the time, and it has become a lot more effective for him. His K% on that pitch has jumped from 10% to 18%, and his SwK% on it has increased from 4% to 8%. Whether Hammel can sustain his hot start will be determined by his control. He hasn't posted a sub-3.0 Ctl since 2010.
Aaron Harang (RHP, ATL) has enjoyed a mini re-birth so far in 2014: 2.98 ERA, 1.18 WHIP, 9.7 Dom, 3.2 Ctl, 40% GB%, 107 BPV. While his pitch mix has been more slanted towards his four-seam fastball, a tightened slider is the real reason for his growth. He has a high 32% K% on that pitch, along with a 21% SwK%. Both marks are significant jumps from the results he had on those pitches in 2013. At age 36, we're still pessimistic that Harang will be able to continue to ride that pitch to sustained success.
Ian Kennedy (RHP, SD) is pitching better than he has at any time during his career: 9.8 Dom, 2.0 Ctl, 45% GB%, 147 BPV. He has added velocity to his four-seam fastball, and he's using that pitch a lot more than he has in the past. He is generating more strikeouts (22% K%) with that pitch than at any time during his career. Interestingly, he has a 20%+ K% with five different pitches and a 15%+ SwK% with two separate pitches. The window to get back on the Kennedy bandwagon is closing quickly.
Brandon McCarthy (RHP, ARI) has seen a huge spike in velocity on his fastball from 2013 to 2014 (90.8 mph to 93.0 mph). His cutter has become a legit strikeout pitch for him. He has a 13% SwK% with that pitch. Combined with a strong curveball (35% K%), McCarthy has two legit swing-and-miss pitches. Ignore his near-5 ERA and buy his elite skill set.
Wily Peralta (RHP, MIL) does not have a varied pitch mix. He has a four-seam fastball, two-seam fastball, and slider. He's relying on his two-seamer even more. He had a marginal 10% K% on that pitch in 2013, but it has jumped to a 13% K% so far in 2014. The biggest reason for his early breakout can be found in his 5.0 Cmd against LH bats. If he can sustain that, Peralta has the goods to remain valuable, even with limited off-speed stuff.
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