My writings about baseball, with a strong statistical & machine learning slant.

Tuesday, August 24, 2010

Incomplete thoughts on ground-ball pitchers

I've been out of the baseball loop, focusing on my basketball project. But I still slavishly read Bill James's site, and he brought up a point relevant to my research on pitcher types. In answering a question about Brandon Webb, Bill said:
I've said it a thousand times, but. . .I don't believe in ground ball pitchers. I don't trust them, I don't want them, and I don't believe one should ever invest money in them. In theory, a ground ball pitcher with a good strikeout rate is the best of both worlds. But the problem is, there just aren't any pitchers like that who are consistently good; they all either get hurt or they lose home plate. The only pitcher like that who has had a great career in the last 30 years was Kevin Brown. The overwhelming majority of the consistently good pitchers are the guys who live off of the high fastball--Clemens, Schilling, the Unit, Pedro, Santana, King Felix, Verlander, Sabathia, etc.
When I left off my baseball research, I left off with a classification of pitchers by the type of pitches that they throw. Dave Allen pointed out that I should look at pitchers who throw two-seam fastballs, as those pitchers have become the subject of much sabermetric discussion. Two-seam fastballs induce ground balls like no other pitch, and the value of ground balls for pitchers has become a hotly debated topic. (By hot, I mean that multiple analysts are competing to show how much value ground balls really have for pitchers.)

I created a new category of pitchers, centered around those that throw a high percentage of two-seam fastballs. Indeed, this category of pitchers had very high ground ball rates (something like 6% higher than average), but also lower strikeout rates (about 0.5 K/9 less than average). I was going to write an article about whether or not this "tradeoff" is worth it.

But Bill James brings up a better point. Who are the great two-seam fastball ground ball pitchers out there? Clearly Brandon Webb has to be the most famous example. But let's consider the others. I only had reliable two-seamed fastball data for 2009, so all examples have to be from last year. Here are the most name-recognizable pitchers who classified as "type 8: two-seam fastball pitcher" by my scheme. All data courtesy of PF/X posted on FanGraphs.

Pitcher 2009 FT% 2010 FT%
Joel Piniero 28% 49%
Brian Matusz 14% 21%
Scott Kazmir 10% 0%
Rick Porcello 22% 52%
Francisco Liriano 12% 46%
Fausto Carmona 9% 33%
Chien-Ming Wang 23% NA
Carlos Silva 43% 50%

Ignoring Scott Kazmir, who no longer throws two-seam fastballs, and the hobbled CM Wang, is there anything we can generalize about the two-seam fastball pitchers?

First of all, none of them are backing off the pitch. This is selective, since I chose the most recognizable proponents of the pitch, and PF/X pitch classifications are not consistent year to year. Still, I think this suggests that two-seam fastball pitchers are on the rise. How is it affecting their stats?

All of these pitchers are recording high GB% stats on the season, except for Brian Matusz. Joel Pineiro leads with 56%, and none of these guys except Matusz are below 45% (league average is in the low 40% range). Accounting for randomness, these pitchers are all getting high ground ball rates, in part due to their use of the two-seam fastball. However none of them except for Liriano are having top-level season. Here are the 2010 strikeout rates (K/9) for those pitchers:

Pitcher 2010 K/9
Joel Piniero 5.7
Brian Matusz 6.9
Rick Porcello 4.5
Francisco Liriano 9.8
Fausto Carmona 4.8
Carlos Silva 6.3

Not surprisingly, Francisco Liriano has a 3.45 ERA, despite a very unlucky 0.350 BABIP. He is having a "Kevin Brown" season, as Bill James would describe it, with both high GB% and high strikeout rate. However the other pitchers have league-average strikeout rates at best. Fausto Carmona has the stuff (93 mph average fastball) to be a high-strikeout pitcher, but he has never realized that potential (even during his 19-win season in 2007, he was a low-strikeout pitcher). It is very unlikely he will become even a league-average strikeout pitcher at this point in his career. Joel Pineiro was dominant earlier this season when he was getting 70% ground balls, but his ERA and FIP have settled around 4.0 now that his ground ball rate is a more sustainable 56%. Without above-average strikeout rates, a pitcher's long term ceiling might be that 4.0 ERA. Not bad, and worth a couple of WAR, but not in the elite pitcher echelon.

Brian Matusz in an interesting case. He was a high strikeout guy in the minors, and has had a league-average strikeout rate over his first 200 major league innings. He throws a two-seam fastball according to PF/X, but he doesn't get high ground ball rates. I'm not sure what's going on there. Maybe he just doesn't belong in this list.

Overall, though, I think Bill James's point is well taken. You can't be a great pitcher on ground balls alone, at least not over a course of several years. You need to have strikeouts. Francisco Liriano might be the next pitcher to maintain high GB rates with high strikeout totals. But he'll have to prove it over more than one season.

Projecting Liriano in April

I'm happy to see Liriano having a great season. He's endured a few injury setbacks, and I'm happy to see him finally come back to form. Also, my pitcher projections were very favorable for him, and it's always pleasant to be right on something like this.

In the projection I published in April, here is what my system predicted for Francisco Liriano in 2010:

  • 159.6 IP; 20.9 VORP; 4.31 ERA; 4.24 FIP

Of course, he has been much better than that. But it was bold of my system to project him for a full season, and to be in the top 50 most valuable pitchers in MLB. In 2009, he was 5-13 with a 5.80 ERA in 136 IP. I think this is a real win for my injury-based projection adjustments.

With the season finishing up, I will go my predictions more systematically. As you can see from the link above, I was off on quite a few of them. I was probably more pessimistic on Cliff Lee than most (in part due to his injury in camp). I got fooled on Javier Vazquez. And I thought John Lackey would be a workhorse, rather than a dud.

But this is all a topic for a future post. Til then...