I was recently looking through fangraph's pitching value stats when something struck me. It involved the effectiveness of the cutter, a pitch made famous by Mariano Rivera but thrown by several other pitchers with a great deal of effectiveness.
In the last two years among qualified starters, 17 pitchers can be said to use a cutter often enough that it can be considered a legitimate part of their repertoire. Those 17 pitchers are: Roy Halladay, Scott Feldman, Dan Haren, Jon Lester, John Danks, Andy Pettitte, Chad Billingsley, Jason Marquis, Doug Davis, Jamie Moyer, John Garland, Mark Buehrle, Brian Bannister, Cliff Lee, James Shields, Nick Blackburn, Jarrod Washburn. That is an interesting cross-section of players. We have power pitchers, finesse pitchers, stars, mediocre players, lefties and righties.
The big point however is that these are the only starting pitchers who throw cutters routinely in baseball right now and the striking thing is that all of their cutters are effective. With every other pitch available to a person you will find some that are very good and some that are very bad. For every Zack Greinke slider there is a Braden Looper slider, for every Adam Wainwright curve you have a Joe Saunders. Not so, with the cutter. Out of those 17 pitchers, the worst cutter belongs to Jarrod Washburn, but even his was just barely a below average pitch. Conversely there are a lot of pitchers whose cutters are extremely effective.
Out of the 17 pitchers listed, for nine of them, the cutter is their most effective pitch. Those nine include Halladay, Lester, Haren, Danks, and Pettitte who are some of the best pitchers in baseball right now. Just as interestingly, in zero cases is the cutter the worst pitch in any of those players' repertoire.
The data for the relief pitchers in baseball is actually very similar to this, for most of the players who employ a cutter, it is their best pitch and for almost no one who uses is regularly does it have a negative value.
All of this data seems to suggest that the cutter, in general, is an incredibly useful pitch to learn and use. It seems that more pitchers are learning it every year and it has helped their careers immensely. Scott Feldman only starting using it often this year and turned himself from an average reliever into an above average starter. Roy Halladay's spike in strikeouts recently corresponds directly to his increased use of the cutter. John Danks had a poor rookie season in 2007, learned a cutter in 2008 and turned himself into a borderline all-star. These are perfect examples of how learning this pitch has greatly altered a players career for the better. All of you pitcher out there take note; if you want to become a better pitcher, learn a cutter!