Looking at the Aces’ Cutters

I could sum up this post with a saying from our good friend, ZWR: so cuttered. But sadly, I only have a fraction of the wit found over at Zoo With Roy, so instead I’ll go ahead and stick to nerdy statistical stuff.

At least from an anecdotal perspective, it certainly appears as if the cutter—a laterally breaking pitch similar to a fastball—has become increasingly popular in the past few years. The Phillies have played a huge role in promoting this narrative as their three aces make significant use of the cut fastball. Of course, Mariano Rivera, the man who utilized nothing but the cutter to become the best relief pitcher of all time, is the most well-known idealization of the pitch. But Roy Halladay is likely the second guy to come to mind, and Cliff Lee probably isn’t far behind. In 2011, the big three rode their way into history by heavily relying on throwing cutter after cutter.

In order to see how each of the aces made use of this pitch last year, I gathered some data from Brooks Baseball. First, let’s take a look at the basics.

Halladay throws lots of cutters. Relying on it nearly 50% of the time made him the biggest proprietor of the cutter among starters last season. Lee and Hamels don’t throw it quite as often, but using it one out of every five pitches is still significantly more than the rest of the league. Halladay’s is the fastest, and it’s not really close. This is a peculiar point—a pitcher’s cutter velocity usually sits around 3-4 mph slower than his fastball, and Doc’s regular sinker usually hangs around 92 mph. Of course, it’s hard to draw any sort of real conclusion from this, but the minuscule difference in velocity between the two pitches could possibly be a factor in explaining why he’s been so damn successful with the pitch.

Moving on, let’s look at the pitch outcomes:

Lee’s cutters ended up being strikes more than those from the other two pitchers, but there’s not much surprise there. Likewise, Lee and Halladay had the pitch fall in for a called strike at the same rate whereas Hamels was a bit behind. Batters swung at Lee’s cutter more often than they did against Doc and Hamels, and they also swung and missed at a higher rate.

The batted ball data is where things start to get more interesting. While Halladay and Lee both have impressive batted ball profiles when it comes to the cutter, Hamels is in another galaxy. His 2011 cutter was a groundball inducing machine with a GB/BIP rate north of 60 percent. This likely explains a fair amount of his recent transformation into a groundball pitcher. In 2008, his GB% was 39.5 percent. He added a cutter in 2010, and by 2011 his GB% ballooned to 53.3 percent.

An also-impressive line drive rate supports the notion that Hamels’ cutter is particular adept at inducing weak contact. By looking at 2010, the only other year that Hamels had a a cut fastball in his arsenal, we can see that this doesn’t appear to be a fluke—he also had a good batted ball profile with the pitch. While many argue that he was the beneficiary of good luck last year because of his .255 BABIP (.290 is about league average), the data seem to suggest that an increased reliance on the cutter has provided him with an upgraded ability to keep batted balls from falling in for hits. Of course, BABIP is known to fluctuate quite wildly from year to year, so I suppose an additional year will help us further test this claim.

Lastly I’d like to pose this question: when does each pitcher most often throw their cutter? Going through situational count data can give us insight into this. Click to enlarge the graphic below.

Halladay loves to throw the cutter in situations where he’s looking for a surefire strike: 1-0, 2-0, 3-0, and 3-1 especially. Lee’s behavior is similar, but to a lesser extent. This shouldn’t come as a shock—these two simply refuse to walk batters, and if they’re behind they’re still going to attack the zone. Hamels is a bit different with the exception of a 3-0 count. His cutter frequency actually drops off a bit in the aforementioned situations, perhaps suggesting he has less confidence when it comes to spotting the ball with this pitch. The aggregate data suggest just that as his cutter’s strike % and called strike % are lower than those of Doc and Lee.

This isn’t the first time we’ve looked deeper into what made the aces so awesome last year. By now, nearly anything that could be written about last season’s rotation has been written. After all, we already knew that the Phillies like to hurl horizontally-moving baseballs towards home plate. But hopefully this information provides a bit more insight into just why they left hundreds of batters so cuttered.