Miami Marlins Josh Johnson Has Latest Weapon In Curveball

MIAMI, FL - SEPTEMBER 01: Pitcher Josh Johnson #55 of the Miami Marlins throws against the New York Mets at Marlins Park on September 1, 2012 in Miami, Florida. The Mets defeated the Marlins 3-0. (Photo by Marc Serota/Getty Images)

The Miami Marlins are continuing to watch for a number of things with earnest for the month of September, and one of those things is the continued health and well-being of Josh Johnson. Johnson is continuing his trek back from shoulder injuries in 2011, having completed 165 1/3 innings this season and being on track to potentially finish 32 starts this season.

Johnson's season itself has not been a major success, as his 3.86 ERA is not quite up to the usual par for Johnson. Still, Johnson has not been bad at all, as his ERA and 3.32 FIP clearly show. One of the newest aspects of Johnson's 2012 season of good play has been the addition of his curveball. Last season, Johnson began working in a curveball in a few appearances here and there, and this season the usage of his curveball has gone up. In his latest start, Johnson threw the curveball 20 times in 105 pitches against a lefty-laden New York Mets lineup.

So just how good has the curveball been, and can it be used consistently to get lefties out for Johnson?


According to Pitch F/X classifications, Johnson has thrown the curveball in just about 14 percent of his pitches thrown. According to the re-classifications by Brooks Baseball on Johnson's player card, this number is confirmed. For Johnson, it is his third most used pitch, behind his fastball (presuming he throws just one type of fastball) and his slider.

More pertinent to the conversation is the fact that Johnson seems to have supplanted the use of his changeup with the curveball. Overall, the curveball is being used around twice as often if not more than the changeup, after years of his changeup being the primary pitch used against lefties. After multiple seasons, this is the first year in which Johnson's changeup use has fallen below the use of his curve.

In addition, despite the fact that the curveball is a pitch that can be used to both lefties and righties and is at worst a little better against opposite-handed hitters (though not to the extent of the changeup), Johnson has mostly used it against lefties and kept his fastball-slider combo versus righties. So far this year, 259 of his 343 curveballs thrown have been to left-handers, a 75.5 percent rate.


Once again, we examines pitchers and their pitches using Pitch F/X data and certain statistics regarding their pitch effectiveness. Johnson's curveball is no different.

Johnson, 2012 Zone% B/CS Swing% Whiff%
Curveball 43.7 1.7 34.4 41.5

These are interesting numbers, if only because they show how effective a pitch like Johnson's curveball can be. The most daunting number listed here is the whiff rate of 41.5 percent. Those type of swing and miss numbers are befitting of an out pitch against batters, and they likely are quite favorable when compared to other out pitches. Just as a comparison, let's look at his numbers versus his slider.

Johnson, 2012 Zone% B/CS Swing% Whiff%
Slider 37.6 5.8 53.8 39.5

The numbers shown here are highly intriguing. Both pitches are thrown in the strike zone at similar rates, but the curveball is more often taken for strikes than the slider. At the same time, the slider is a more enticing pitch at which to swing, but both pitches also get similar numbers of swings and misses.

Consider the differences in the number of strikes Johnson gets with his curveball versus his slider. On the pitches taken, Johnson's curveball is generating 17 more strikes per 100 pitches than Johnson's slider. In terms of pitches swung at, Johnson is generating just about seven more strikes from his slider than the curveball. Keep in mind that the strikes off of swings and misses are turning would be balls in play or foul balls into true strikes, whereas the 17 bounus strikes on taken pitches are converting balls to strikes; the latter is a much greater impact. Overall, the slider has been less effective than the curveball at the rate at which he has thrown the two pitches.

The advantage of the slider for Johnson presumably is that he is able to throw it against both lefties and righties with similar effectiveness. For example, his whiff rate on the slider is at 39.8 percent versus righties and 38.7 percent versus lefties. However, at least in terms of whiffs, the curveball seems to have similar effectiveness versus both sides as well, with a 41.7 percent whiff rate on lefties and a 40.8 percent rate on righties. Given some of the early returns and the fact that the curveball is well-known to be a pitch that can be neutral, and you get the sense that Johnson could use the curve more towards righties as well as lefties.

Johnson's curve is his just the latest weapon in his bag of tracks against opposing hitters. It has supplanted his changeup as his go-to pitch versus lefties, and according to the early returns, it seems it is not only effective against lefties, but just as effective as his slider overall. In fact, the pitch seems so effective that he could throw it to either side of the plate easily. With that in mind, perhaps it worth investigating using the pitch more often like he did in his last start, this time more towards right-handers as well as lefties. It gives them something else to consider when dealing with his already back-breaking slider and the good fastball.

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