Rick Porcello Needs to Work on His Fastballs

This baseball season has been rough for the Boston Red Sox, and it has been especially rough on Rick Porcello. The starting pitcher came over from the Detroit Tigers with high hopes, but has faltered in a big way. Ian York takes a look at the fastballs thrown by Rick Porcello to see if he can figure out what’s wrong.

Rick Porcello has had, at best, mixed results this year. While he has pitched a number of good to very good games, he has also thrown a number that were simply awful. Before the All-Star break, we looked at Porcello’s season, and didn’t see any blatant issues with his pitches. We suggested at the time that part of his problem was mislocating his pitches, since his four-seam fastballs have been a little higher in the strike zone than they were last year. However, we didn’t find that a completely convincing explanation.

Now, the always-insightful Brian MacPherson has suggested an alternative explanation:

Porcello gets into trouble is when he inadvertently blends those two fastballs. The worst pitch Porcello throws is a two-seamer that he tries to throw as hard as his four-seamer, robbing the pitch of its movement – often with disastrous results. 

Could this be an explanation for Porcello’s troubles this year? We looked at Porcello’s four-seam and two-seam fastballs this year and last year. Here are scatter plots of speed vs. amount of break on each:

(These charts are basically closeups of those shown in the previous article, where we showed more characteristics and all the pitches.)

It does look, here, as if the four- and two-seam fastballs blur more into each other this year than they did last year. It is complicated by a number of pitches that are clearly misclassified by PITCHf/x – for example, the so-called four-seams (red dots) that have significant break and slower speed, which are almost certainly really two-seam fastballs.

We can see trends more easily using a KDE plot:

Now, a few things show up between seasons. Porcello is tending to throw his four-seam a little faster this year than last year, while his two-seams are about the same velocity. Along with that, as expected, his four-seam shows slightly less break on average.

More significantly, there is an outcropping on the right side of the four-seam cluster, those pitches with a break length between about 4 and 6 inches and with a speed less than 92 mph, that are beginning to overlap with the two-seam cluster. That group was not present last year, where the separation between these pitch types was much more clear.

What happens when Porcello throws those pitches? I pulled out that group, and labelled them as “mixed” pitches:

Then I asked how many hits, and how many bases, were achieved on each of the three groups:

Pitch type Hits per 100 pitches Bases per 100 pitches
Four-seam 5.5 8.7
Two-seam 8.1 10.4
Mixed 10.6 17.5

Porcello’s pure two-seam, with its greater break, is hit more often than his four-seam, but not as hard (since the increase in bases per pitch is less than the increase in hits per pitch). The apparent effectiveness of the four-seam is probably heavily dependent on Porcello’s use of the two-seam, since it means batters have to make a last-minute assessment of the break of the pitch; if Porcello reduced the use of his two-seam, the four-seam would undoubtedly become much less effective. (Not to mention that the two-seam is more likely to bring about double plays and weak contact, which aren’t considered here.)

But the mixed pitches – that is, pitches that are slower than a pure four-seam fastball, but that don’t move as much as a two-seam fastball – are being destroyed. They are being hit nearly twice as often as the four-seam, and even harder.

In MacPherson’s article, he quotes Alex Avila as saying:

“Ricky, at his best, he’s not throwing as hard,” Avila said. “Sometimes when he’s throwing that 93- or 94-mile-per-hour sinker, it doesn’t have as much movement as, let’s say, at 91. That’s the tough part.”

This group of mixed pitches doesn’t exactly fit Avila’s description, since they are not faster than the general run of two-seam fastballs. (Including the faster pitches in this group actually reduces the effect, with hits and bases per pitch looking more like general two-seam fastballs.) However, it is still quite possible that these pitches are the result of overthrowing the two-seamer, flattening out the movement while not gaining enough velocity to be effective.

This still does not seem to be a complete explanation for Porcello’s uneven 2015. Game by game, the number of “mixed” pitches does not seem to correlate well with the game’s WHIP; in some of his worst games, he has shown good separation of his four- and two-seam fastballs. However, it does suggest one aspect that Porcello may be able to control going forward.

Ian York has written about rookie struggles, an impressive start by Eduardo Rodriguez, Mike Napoli and the effect the strike zone is having on him, and the effect of better bullpens on offensive strategy.

Follow Ian on Twitter @iayork.

Check out Ian’s look at new Kansas City Royal Johnny Cueto.

About Ian York 208 Articles
Ian is an immunologist and virologist who lives in Atlanta with his wife and two sons. Most of his time is spent driving his kids to baseball and soccer games, during which he indoctrinates his children on the glories of Pedro Martinez, the many virtues of the Montreal Expos, and other important information.


  1. Interesting that you quoted Avila about him, a guy who caught Porcello for years and knows what works and what doesn’t. One thing that’s been noted on by others is that Porcello has pitched very well when Ryan Hanigan catches him this season (3.16 ERA), but he’s been dreadful with Sandy Leon (9.28, 7 HR in 21.1 IP) and bad with Swihart (5.63 ERA). And Hanigan was quoted as saying that he thought Porcello’s problems were due to pitch selection. I wouldn’t think that a young catcher would have that much trouble working with Porcello’s repertoire, especially since Buchholz was lights-out with Leon. But it sure looks like Hanigan (and Avila) know something.

  2. Overthrowing a two-seamer seems like such a dumb mistake. A two-seamer is supposed to be a pitch that sacrifices velocity for movement. (Wouldn’t that statement confuse a physicist?)

    Maybe there’s truth to the idea that he’s “pressing” and trying to earn that big extension… but this seems like a very correctable problem.

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