Yankee fireballers Nathan Eovaldi and David Carpenter have a lot in common. They both possess premium velocity, they both have effective sliders, and despite being from the dirty south, they both are working on a pitch primarily used in Japan. Towards the end of last season Eovaldi was said to be working on a splitter, after struggling with his changeup throughout his career. Carpenter has been toying with the pitch this spring training, according to ESPN's Buster Olney:
Scouts are saying that David Carpenter looks tremendous for the Yankees this spring -- power stuff, augmented by a splitter he is trying.
— Buster Olney (@Buster_ESPN) March 17, 2015
Carpenter also never quite developed a working changeup. Eovaldi and Carpenter are far from alone. Countless hurlers never really get the hang of the changeup and never truly reach their potential as a result. Yankees past and present such as Dellin Betances, Joba Chamberlain, and Bryan Mitchell have all shown elite velocity but could never start at the MLB level, due in part to the lack of a secondary pitch for lefties. Obviously, there is hope for Mitchell, but he doesn't even have a third pitch in his arsenal yet.
Betances, Chamberlain, Mitchell, and many other power pitchers have managed to develop killer sliders and/or curveballs. A nasty slider has often been associated with high velocity pitchers, from Bob Gibson to Randy Johnson to guys like Garrett Richards and Max Scherzer today. Looking at Pitch F/X data from 2008-2014, there is a weak, yet statistically significant correlation between fastball velocity and whiff rates on sliders:
(coefficient=0.012, R-squared=0.1163, t=5.69, min. 200 fastballs and 100 sliders)
It makes intuitive sense. Pitchers with fastballs in the high 90's usually are the ones getting the nastiest bite on their sliders. However, the correlation is a lot weaker when it comes to changeups:
(coefficient=0.006, R-squared=0.0265, t=2.59, min. 200 fastballs and 100 changeups)
Data for both graphs is courtesy of Baseball Prospectus.
I don't know too much about pitching mechanics, but my understanding is that pitchers use the slider's movement to get hitters out, while the changeup is more effective when used to change speeds within an at bat. A lot of power pitchers never get the hang of the changeup because simply throwing it harder doesn't make it better. As a result, they don't have a pitch for opposite-handed hitters and can never rise to their front-of-the-rotation ceilings.
Enter the splitter. According to Pitch F/X data from The Texas Leaguers, splitters break in the same direction as changeups, but they have more vertical movement and are thrown faster on average. Because the splitter can be more of a "movement pitch" and less of a "change in speed pitch" like the traditional changeup, power pitchers should, in theory, have more success using it. At an average 87.27 mph, Masahiro Tanaka's splitter is just five miles per hour slower than his fastball. Just five mph of separation between a pitcher's fastball and changeup would make most pitching coaches cringe. But the extreme, last millisecond drop on Tanaka's splitter makes it one of the best pitches in the world.
From a developmental standpoint, it should also come easier to high velocity pitchers than a normal changeup would. Pitchers who have grown up throwing significantly harder than their peers usually never have to develop their command as much. When they are asked to learn to throw a pitch like the changeup, which is virtually useless without excellent location, it makes sense that they have a hard time. Pitches with extreme movement generally don't require as precise command since their trajectory is inherently unpredictable.
While Japanese pitchers such as Yu Darvish, Koji Uehara, Masahiro Tanaka, and Hisashi Iwakuma have practically made a living off of the splitter, the changeup is much more popular among American pitchers. However, young power pitchers like Jeff Samardzija, Kevin Gausman, and Danny Salazar have all opted for the splitter in lieu of the change, all generating whiff rates north of 40%. Getting that many swings and misses on any pitch would be very exciting for anyone.
Developing a good changeup will never be easy for young pitchers with live arms. Perhaps the splitter can take its place and help promising young hurlers reach their ceilings going forward. Theoretically, it should be easier to learn as well. As exciting as guys like Dellin Betances are, seeing promising prospects relegated to the bullpen because they could not develop another secondary pitch definitely gets old after a while. Last season, the splitter was one of the least frequently thrown pitches in baseball. Knowing how analytics-oriented teams are becoming, it is only a matter of time before an MLB organization makes the splitter their thing. If Carpenter and Eovaldi experience success with the splitter, the Yankees could be that team.