Carpenter’s Pitch Selection

Sports Illustrated’s Tom Verducci chronicled Chris Carpenter’s transformation this season in an article published during St. Louis’ World Series run. In it, the Cardinals’ ace credited pitching coach Dave Duncan with his professional turnaround. The premise of Verducci’s story was a simple one: Carpenter — then with Toronto — began his career as a hard-thrower with a four-seam fastball, curveball and not much in the way of command. But after arriving in St. Louis prior to the 2004 season — voilà! — Carpenter learned a two-seam fastball and Duncan showed him how to command the bottom of the strike zone. In Carpenter’s words:

The classic Dunc game: keep the ball at the bottom of the strike zone and you’re going to make it harder for the other team to score. It’s not so much about trying to hit corners as it is pounding the bottom of the zone with movement.

With this in mind, it’s no surprise that, for 2009 and 2010, Carpenter threw almost all of his fastballs with a sinker grip. He also threw a cutter, a curveball and a change — but we won’t deal with the curve and the change much in this post. The images below show spin-deflection charts for his fastballs and cutters from some of his 2009 and 2010 starts so that we can see his pitch movement, on a game level.

(click to enlarge)

You can see that, in these examples, there are a lot of pitches that move laterally about 8 to 10 inches – those are the fastballs with the two-seam grip that Duncan taught Carpenter. Some starts have pitches that look a little bit straighter, with less sink and tail to them. These are the four-seam fastballs, which look rare, based on the games selected above. The pitches on the other side of the axis are cut fastballs, which move away from a right-handed hitter.

Now let’s look at those same charts for three 2011 starts.

The four-seam cluster is now very prominent. Tracking the progression of his pitch selection confirms that Carpenter’s reliance on the four-seam fastball was new in 2011, and it really started to become prominent by the end of May.

The next thing I wanted to examine was the effect that the ball/strike count had on Carpenter’s pitch selection. My apologies if the graph below looks a little bit funky: it compares Carpenter’s 2011 pitch selection to his 2010 pitch selection, split up by each of the 12 ball/strike permutations (which are sorted by increasing run expectancy). Positive numbers show an increase in usage from 2010; negative numbers show a decrease. Particularly against lefties, Carpenter’s pitch selection has changed the most on two-strike and in 3-0 counts.

So Carpenter turned himself into a different pitcher in 2011. But what kinds of implications did his change in pitch mix have? The following table has some generic PITCHf/x metrics on the two-seam and four-seam fastballs over the 2009 through 2011 seasons.

            #        mph      Swing    Whiff    Ball     Zone     GB%
Two-Seam    4219     92.0     .448     .093     .329     .523     .544
Four-Seam   755      92.7     .465     .194     .331     .499     .333

Two-seam fastballs typically get grounders but not many whiffs; four-seamers typically get whiffs but not many grounders. Carpenter’s pitches are no exception. In fact, his two-seamer is better than average (~53%) at getting grounders, and his four-seamer is better than average (~17%) at getting whiffs. Basically, you could say that they’re both “plus” pitches for their respective purposes and relative to pitch type.

Overall, Carpenter was much less of a ground-ball pitcher in 2011 than he has been throughout his career in St. Louis. Dating back to 2004, he’s been at ~52% ground-balls-per-pitch-in-play, but that rate dropped to only 45% this year (including postseason starts). His strikeout rate — including postseason starts — was just under 7K/9, which is where he’s been in the past three years. The biggest difference with Carpenter’s performance this year was his lack of grounders — and this can be explained by the sudden increase in four-seamers. It’s true that his new pitch was better at getting swinging strikes — compared to his sinker — but his curve and cutter are better than both. So if the four-seam fastball is taking the place of curves and cutters in two-strike counts, he’s putting himself at a disadvantage, particularly because the pitch yields an extreme number of fly balls. The evolution of Carpenter’s repertoire is puzzling, especially considering how much credit he’s given to Dave Duncan for kick-starting his career.

PITCHf/x data are from MLB Advanced Media and here are courtesy of Joe Lefkowitz’s tool.  (Two of Carpenter’s games since 2009 are missing in my dataset.) 

A note on the strike zone: the definition of the strike zone here is the one Mike Fast adopted in his Baseball Prospectus articles, “The Real Strike Zone, Part 2” and “A Zone of Their Own.”  The vertical zone is fixed from 1.75 feet above the ground to 3.4 feet above the ground. The horizontal zone to LHB is 1.2 feet inside from the center of the plate to 0.81 feet outside; and the horizontal zone to RHB is 1.03 feet inside from the center of the plate to 1 foot outside. 

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10 Responses to “Carpenter’s Pitch Selection”

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  1. Luke says:

    Does the increased usage of the four-seam fastball correlate with Carpenter’s second half “surge”?

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  2. Andross says:

    Part of the change in pitch selection may be a response by Carpenter to the Cardinals poor infield defense, which negated many of the advantages of selecting pitches that encourage GBs.

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  3. Bob Hudgins says:

    I think Andross is on to something, but I’ve watched Carpenter closely for years. He had trouble–especially earlier in the season–commanding his curveball. It was just a floppy, purposeless offering. You could see that through the whole season.
    It was only when he could command it, and was determined to use it, that he was more effective. He threw more curveballs, and good ones, in NLDS Game Five than any other start this season.

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  4. says:

    Kudos to Carp for changing his ways to fit the team he has around him. If I had Theriot and Schumaker up the middle behind me for most of the year….. I sure as heck would be trying for more swings and misses instead of getting ground balls. If Furcal is resigned, maybe he can mix the best of both worlds in 2012.

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  5. Greg H says:

    I’m not persuaded that Carpenter resorted to more four-seamers in 2011 in response to his defense. An outfield of Holliday, Jay, and Berkman shouldn’t encourage pitchers to induce fly balls.

    I suspect one of two things caused Carpenter to throw fewer sinkers. First, Carpenter may have lost confidence in his ability to command his sinker. This may be a mechanical issue or psychological or a combination of both. The four-seamer is a much easier pitch to command because it has less movement. Second, Carpenter may have resorted to throwing more four-seamers to reduce the risk of injury or manage discomfort in his elbow. A sinker requires the pitcher to pronate his wrist very early. While the pronation isn’t as severe as in a screwball, it still places additional strain on the elbow. In contrast, when throwing a four-seamer, a pitcher such as Carpenter with a high three-quarters arm slot will naturally pronate his wrist closer to the point of release and as he follows through. This natural pronation is believed to actually reduce strain on the joints, although orthopedic surgeons who specialize in sports medicine are not unanimous in the benefits of pronation. In any event, the forced early pronation in a sinker can be a hard pitch on the elbow.

    It has been well established in numerous articles that Carpenter all but abandoned his slider in 2011 in exchange for a cutter. In the postseason, I saw Carpenter throw very few sliders but a fair amount of cutters. According to Pitch F/X, Carpenter threw sliders about 26% of the time, but that is almost certainly a result of false pitch identification – the technology is confusing a cutter with a slider. Carpenter also threw a lot fewer curveballs in 2011 than he did in 2009 and 2010.

    So Carpenter threw fewer breaking pitches and sinkers in 2011 – pitches that will put additional strain on the elbow and may be difficult to throw properly with a tender elbow.

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    • Maybe Carpenter, realizing with Wainwright down, he was going to get a lot more work, chose a pitch repetoire he could sustain over what was going to be a grueling season. If so, I would imagine, he and Duncan made the concious decision to make the change. It’s was also my impression that Yadir worked his outings a little differently as well to fascilitate Carpenter’s approach. There were certainly a lot more looks into the dugout by Molina than one usually sees with Carpenter on the mound.

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      • Greg H says:

        Good point. It may also just boil down to Carpenter, the coaching staff, and Molina concluding that hitters were having more success against Carpenter’s sinker than in the past, and thus they made the adjustment by calling for more four-seamers. If that’s the reason, it still begs the question as to why Carpenter’s best pitch betrayed him in 2011 – is it a result of Carpenter not having as good a breaking ball to compliment the sinker, and thus hitters were able to lock in better on the sinker?

        In any event, I cannot accept the argument that this adjustment was made in response to the Cardinals defense. Carpenter has always been able to miss bats, which is one of the reasons he has been an elite pitcher for so long, setting himself apart from the garden-variety sinker/slider pitchers that populate MLB rotations. I don’t think he felt compelled to throw more four-seamers with the intention of missing more bats and inducing fewer grounders. He was still a ground-ball heavy pitcher in 2011. In fact, his ratio of GB to FB was practically identical in 2010. I think this is the classic case of an aging pitcher making adjustments to get hitters out. And it worked pretty well for him in the second half of the season.

        I think the more interesting narrative is that Carpenter, like so many pitchers, relied more heavily on a cutter in 2011 than in the past (although I think he started throwing cutters as early as 2008) and all but ditched the slider – a pitch that had been pretty effective for him.

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      • Greg,

        you know, I wonder about arm tenderness as well. Wilson with the Giants walked away from his slider as well for the cutter this year until he finally came up with tendonitis in August.

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