May 18, 2013; Miami, FL, USA; Miami Marlins starting pitcher Tom Koehler (34) reacts after giving a home run to Arizona Diamondbacks right fielder Gerardo Parra (not pictured) during the first inning at Marlins Park. Mandatory Credit: Steve Mitchell-USA TODAY Sports

Tom Koehler Sparkling Performance Against Dbacks- A Pitch F/X Analysis


One of the reasons that I love baseball is the variety of outcomes and styles that it provides fans. Fans of pitching can see a start by a power pitcher like Jose Fernandez and breakdown how he did it. But there is more than one way to skin a cat, so to speak, the way that Jose Fernandez dominated the Phillies a couple of weeks ago is entirely different from the way that Tom Koehler handled an impressive Arizona Diamondbacks lineup tonight. Koehler looked to be in for a rough night as Gerardo Parra hit a grooved fastball at 94 mph out on the first pitch of the game. But Koehler settled down went 6 IP, allowing that single run off the Parra dinger, with 2 walks and 7 strikeouts on 99 pitches–68 of them strikes.

The age-old adage, is to “get ahead early,” that is to say to throw first pitch strikes. Koehler faced 23 batters in 6 innings, he threw ten first pitch strikes, and had three one-pitch at-bats; the homer to Parra, and two groundouts one by Miguel Montero and the other by A.J. Pollock,13 of the 23 batters he faced had 0-1 count, homered, or were retired on the first pitch. The results of Koehler’s plate appearances follows.

What is particularly interesting to me in that chart are not only the 7 strikeouts but the strikeouts that came on the cutter and also on the curveball but less so. According to pitch F/X data Koehler threw six sliders and got three whiffs, including two strikeouts; one of Paul Goldschmidt in the first inning and one by Gerardo Parra in the third. Those are both demarcated by a six on a black dot on the graph above. The effectiveness of Koehler’s cutter tonight is something that is worth explaining. In the graph below.

Fastballs thrown by right handed pitchers usually rise and either have “cut” or “tail” meaning that the ball moves in to right handed batters in the former and away from from right handed batters in the latter case. Koehler’s fastball “tails” away righties and thus “cuts” into lefties. The cutter can be used to amplify this effect, when facing a right-handed batter who is expecting a “tailing” fastball at 94 mph, it is easy to use a slider to throw of his balance, and vice versa. Koehler’s cutter as above shows, has a lot of horizontal movement but not much vertical movement and is thrown at around 90 mph. The two strikeouts that came via slider; one of Goldschmidt and the other of Parra plays off that effect. Parra’s 7 pitch strikeout in the third inning, shows this well.

Pitches 1 and 6 were fastballs that severely “cut” or “bore” into Parra at 95 mph while pitch 7 the strikeout cutter (effectively a backdoor slider) as pitch F/X designated it comes in at 90 mph and despite the “cutting” effect of the fastball to a left-handed hitter the cutter still functions as pitch that can throw a hitter off balance. Koehler’s at-bat against Parra in the third shows that the value of working the strike zone both in and out as well as up and down. The relative movement inside the strike zone of a pitch like a cutter can force hitters to offer at pitches they would not otherwise. Koehler also recorded three strikeouts via the curveball, the method of how a curveball works was covered in my last article and is effectively about speed difference and how it changes hitters eye levels. The curveball not the changeup is the four seam fastball’s Bizarro twin.

I also want to point out that the cutter works because it is a pitch that like the slider is nearly fastball speed but has much more horizontal movement, causing batters to chase the pitch, expecting it to be a fastball and thus swing and miss.

Koehler was effective tonight for three reasons, he “got ahead” in the count, had good fastball velocity averaging 94 mph, and was able to get swings and misses on his secondary pitches, the cutter and the curveball. The cutter was effective especially in the two at-bats against Goldschmidt and Parra, because it forced whiffs based on his fastball’s movement. The curveball is effective because he was able to control it, generating swings and misses based on the principles of slowing bat speed and changing eye levels. If a right-handed pitcher that can work his fastball at 94 mph can throw two secondary pitches for strikes, a cutter/slider or curveball/changeup he can be successful against many major league lineups. One breaking pitch that can get swings and misses based off of fastball movement and one breaking/off-speed pitch that make hitters whiff with its relationship to fastball velocity.

That explains the three main kinds of non-sinker/splitter dependent pitchers. Fastball/Slider guys like Yu Darvish, Fastball/Curveball pitchers like Jose Fernandez and Fastball/Changeup guys like Justin Verlander.

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