It’s Time to be Concerned About Zack Greinke’s Fastball

Zack Greinke (Brett Davis-USA TODAY Sports)
Zack Greinke (Brett Davis-USA TODAY Sports) /

Nobody expected Zack Greinke to repeat his historic 2015 season when he signed as a free agent with the Arizona Diamondbacks over the winter to become the ace of the Snakes’ staff.

Those numbers don’t get repeated unless your pitching in the deadball era, but the Diamondbacks and their fans expected way more from Greinke than what he has mustered so far.

Despite pitching to a 2.77 ERA across 13.0 innings pitched in his last two starts allowing just two earned runs in both outings, the overall numbers aren’t pretty. Greinke is 3-2 with a 5.15 ERA, his groundball percentage is down, and his HR/FB% has spiked from 7.3 to 11.6.

In addition, his line drive-percentage is up, and his walk-rate is up slighty. None of these numbers should surprise anybody. Even in his solid outings, including the one against the Giants in San Francisco, the crisp location that he is known for is just not as consistent, and he is leaving more pitches middle middle and belt high.

The most concerning part of Greinke’s underperformance to this point in 2016 is the drop off in effectiveness seen with his four-seam fastball. In seven starts this year, tied for the most in the majors with 11 other pitchers, Greinke’s four-seamer is averaging 91.2mph, which is down from 91.6mph last season.

A difference of 0.6 mph doesn’t sound like that much, but it has made a huge difference in damage done off that pitch. Greinke threw 1,399 four-seam fastballs in 2015, and opposing batters hit just .185 off that pitch (49-for-265).

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It’s early, so the numbers are from a small sample size, but opposing batters are hitting .413 (26-for-63). This would explain why Greinke has allowed the most hits (54) in the majors this season. Greinke is either going to have to change eye levels and locations, or he is going to have to put more movement on the pitch and throw it like a two-seamer. He has thrown 35 sinkers and batters are hitting .444 off that pitch.

It might be smart for Greinke to incorporate more curves and slow curves. Batters are hitting just .174 off that pitch, and that might make his fastball more effective. It’s time to be concerned, but keep this in mind before you hit the panic button: The BABIP against his fastball and sinker is .462 and .429 respectively. That is extremely high and suggests that he is either a victim of poor defense or bad luck or both. It will take more pitch counts to fully determine that, because BABIP tends to regress towards the mean (.290-.300), but this might help explain the early season ineffectiveness of that pitch.

That doesn’t invalidate concerns because the same pitch in less than one year’s time, has gone from virtually unhittable to very hittable.