In my previous piece, I found 21 pitchers who showed a marked, sustained improvement between 2003 and 2008. These pitchers had a big jump in their FIP, and they sustained this new level of performance after their breakout year.
In order to find players who put up similar numbers in 2008 to the averages of our breakout pitchers just before they made the leap, I’m going to look at standard deviations. In 2008, there were 142 pitchers who threw for 100 or more innings. Using the Excel function =STDEV, I can find the standard deviation of the key statistics across the sample. What I will then do is add up each player’s total standard deviations from the mean of our breakout pitchers in the stats K/9, BB/9, K/BB, and GB%, and see who totals the smallest deviation from the means.
As I had mentioned, there were essentially two types of pitchers who were on that list: ground ball specialists and power pitchers with low walk rates. Looking at the ground ball specialists, we have the following stats:
The pitcher most similar in 2008 to our ground ball breakout stars: Paul Maholm. Ouch. This is one of those times where I wish I could just make something up, and pretend someone else bubbled to the top. Surely, if I were picking my own favorite breakout candidate for 2009, I’d probably steer clear of a guy on the Pirates. But let’s give him a chance and take a look at his numbers. In 2008, he averaged 6.1 K/9, 2.8 BB/9, and a 54 percent GB%. Really his whole career, he’s been incredibly stable in terms of strikeouts and ground ball rate. He did have a nice little epiphany in 2007 where he learned to bring down his walk rate a bit. And he’s pretty young, only 26 years old. Still, the only way I could rationally see him becoming a star groundballer next year is if he develops a new pitch, or throws a lot more breaking balls.
Below are the stats for the power pitchers who broke out to become stars over the past five seasons:
Four pitchers quickly bubble to the top as being quite similar to those lines: Shaun Marcum, Bronson Arroyo, Dustin McGowan, and John Danks. Arroyo is probably too old to have a breakout season—we’ve seen so much of him in this decade that it’s hard to imagine him breaking away from any of his past numbers. McGowan is an interesting case, because he had great 2007 numbers, including a 53 percent ground ball rate. Following it up with 41 percent in 2008, along with almost a full strikeout fewer per nine innings pitched, makes me less optimistic about him. Marcum and Danks are my two favorites here, because in their cases the numbers back up intuition and observation. Except in Marcum’s case, he’s due for season-ending surgery, forcing him to sit out 2009 while he recovers.
Still, Marcum has had a stable couple of years. His strikeout rate improved a bit last year, while his walk rate remained the same. What interests me about him is the low percentage of fastballs that he throws; in 2008 they only represented 39 percent of his pitches. He’s also shown improvements each year in the rate at which batters swing at pitches outside the zone. Clearly his pitch selection is beginning to baffle hitters a bit more. If the surgery leads to a drop in velocity though, I’d guess he’s finished. We’ve seen how Pedro Martinez, one of the most dominating pitchers in the history of baseball, has fared after a drop in velocity forced him to rely on junkballing. He had a few good years in the National League, but is toast at this point.
Danks is pretty clearly my favorite of the four. The youngest of the group, he’s only 23 years old. In 2008—his second season in the majors—he improved his K/9 by about .3 and his BB/9 by almost a full 1.0. His GB% went from 35 to 43 percent, and batters against him swung at pitches outside the zone 28 percent of the time (up from 18 percent in his rookie season). The biggest warning sign I can find in his 2008 stats is a slight increase in the rate at which he gives up line drives. Still, all other signs point to him becoming a star pitcher in the near future, so look to pick him up maybe a round earlier than you normally would—he may be one of the big draft-day bargains of 2009.