Pitchers change their pitches from season to season, and sometimes even during the season; altering their grip, velocity, arm angle, or pitch sequencing can change a pitch from ineffective to useful, or vice-versa. Which pitchers experienced the biggest changes in their pitch effectiveness from 2015 to 2016?
Using total bases per 100 pitches as a measure of effectiveness, I compared 2015 to 2016. I took pitch classifications directly from PITCHf/x, which means not all of these are correctly identified; I only included those pitch types that PITCHf/x is typically most accurate on – four-seam fastball, curve, slider, and changeup. (I also compared balls per 100 pitches, but with a few exceptions those were fairly stable over the two seasons.)
The full lists are here (four-seam fastball; curve; slider; changeup). Below are the top and bottom five most-improved pitches. A lower TB/100 is better, so a negative number signifies an improvement and a positive number shows the pitch was worse in 2016 than in 2015:
|Hector Neris||12.8||4.7||-8.1||Zach Duke||10||2.4||-7.6|
|Francisco Rodriguez||12.9||5||-7.9||Chase Anderson||8.4||4.5||-3.9|
|Carlos Matias||12.9||5.8||-7.1||J.A. Happ||9.2||5.3||-3.9|
|Mat Latos||14.2||7.7||-6.5||Madison Bumgarner||7.8||4.5||-3.4|
|Matt Barnes||12.9||6.9||-6||Kyle Hendricks||7||4||-2.9|
|Tom Wilhelmsen||9.4||16.9||7.6||Jeff Manship||3||7||4|
|Kevin Jepsen||6.2||14.9||8.7||Jose Quintana||6.2||10.1||4|
|Cesar Ramos||10.1||20.2||10.1||Anibal Sanchez||8.8||13.1||4.3|
|Erik Johnson||9.2||21.3||12.1||Marco Estrada||5.6||9.9||4.3|
|J.J. Hoover||6.8||19.5||12.8||Felix Hernandez||3.4||8||4.6|
|Christopher Rusin||16.1||6.1||-10||Michael Foltynewicz||17.4||8.4||-9|
|Adam Conley||17.3||7.7||-9.7||Eduardo Rodriguez||15.5||7.8||-7.7|
|Rick Porcello||18.1||9.6||-8.5||Scott Kazmir||12.9||6.2||-6.7|
|C.C. Sabathia||10.1||3.9||-6.2||Pat Neshek||12.8||6.2||-6.7|
|Matt Shoemaker||14.4||8.3||-6.1||Tanner Roark||10.8||5.8||-5|
|Colby Lewis||9.2||15.3||6.1||Shawn Kelley||7.1||13.2||6.2|
|Justin Verlander||6.7||12.9||6.2||Michael Blazek||5.9||12.3||6.4|
|Ryan Madson||5.3||12||6.7||Carlos Villanueva||9.1||15.6||6.5|
|Tyler Clippard||6||13.7||7.7||Casey Fien||10.9||19.4||8.4|
|Daniel Hudson||6.2||14.5||8.3||Tony Sipp||6.8||15.6||8.8|
Some of the more interesting changes:
- Eduardo Rodriguez improved his slider somewhat in 2016. In 2015, yielding 15.5 TB/100, it was much worse than league average (possibly related to his pitch tipping issues), while in 2016 (7.8 TB/100) it was slightly better than average. However, he improved the hit rate at the cost of throwing strikes; the balls per 100 pitch rate for his slider went from a slightly worse than average 38.4 in 2015, to 45.3 in 2016 (average for sliders was 35.9), making it among the three worst slider strike rates in baseball. The concern about Rodriguez as a starter has been that he needs to develop a third pitch to complement his fastball and changeup. The slider improved in 2016, but still has a long way to go to be that major-league third pitch.
- Other Red Sox players on the most/least improved lists are Matt Barnes, whose fastball improved dramatically from 2015 to 2016; and Rick Porcello, whose changeup went from abysmal in 2015 to slightly better than average in 2016.
- Hector Neris has the most improved four-seam fastball. In 2015, it was quite a bit worse than average; in 2016, it was quite a good pitch at just 4.7 total bases per 100 pitches. Part of that is undoubtedly due to his velocity, which increased about 1 mph from 2015 to 2016. Another part may be because he started throwing more split-finger fastballs that offer more contrast to his fastball than his slider does.
- It may seem unfair, but Madison Bumgarner’s curveball went from about average, to well above average in 2016. Although he threw his curve slightly slower in 2016 than in 2015 (75.7 mph vs 77.6, respectively) it’s hard to see why the pitch started working so much better in 2016, but he may have altered his mechanics slightly to make it more effective.
- As C.C. Sabathia tries to reinvent himself as a non-fastball pitcher, he turned his 2016 changeup into a real weapon, from an average pitch in 2015.