A review of Zack Wheeler's pitches and pitch results through PITCHf/x through 9 starts

Ralph Freso

About two months ago now, I wrote a post examining through PITCHf/x Zack Wheeler's first start. At the time, all we could really do was examine the movement and velocity of Wheeler's pitches (essentially scouting Wheeler using PITCHf/x), but we could not really make any conclusions about the effectiveness or usage of his pitches.

At this point, Wheeler has made 9 starts, with his tenth start coming up tonight, 8/10/13. His results are as follows:

*Note: All #s below are before Wheeler's start on 8/10/13, as this was written prior to that start. I doubt things will change after his start tonight THAT much.

Platoon IP K/9 BB/9 HR/9 BABIP FIP xFIP
vs LHB 19.0 7.11 8.05 2.37 ..250 7.57 6.55
vs RHB 31.2 7.39 3.13 0.85 .239 3.96 4.04
Total 50.2 7.28 4.97 1.42 .243 5.32 4.98

As you can see, he's not exactly killing it up there. Against Righties his #s are okay, but hardly dominant - Striking out a little over twice those he walks, but not striking out that many batters in the first place. Against left-handed batters, Wheeler has been abysmal - yes, he's walking above 8 lefties per 9, and giving up over 2 HRs per 9 at the same time.

And remember, Most righties see a roughly equal amount of left and right handed batters. So Wheeler has gotten lucky to face over 60% righties! If that evens out and he doesn't improve....yeah, he's gonna have a bad time.

Anyhow, now we do have a decent sample size to make some assessments of Wheeler's pitches. Note that we're still dealing with small sample sizes here with some pitches, but we'll have to make do. So what's causing Wheeler's horrible splits and where can he improve?

Wheeler's Pitches:


Figure 1 and 2: Graph of the movement and Velocity of Wheeler's pitches.

To Read:

Vertical Break: the number of inches the ball drops/"rises" compared to how we would expect gravity to make a pitch drop. So a Fastball with Positive 10 Vertical Movement "*"rises" 10 inches more than it should if gravity was the only force acting on it; a curveball with -10 Vertical Movement drops 10 inches more than a pitch thrown that is just acted on by gravity.

Horizontal Break: The graph is from the view of a catcher or umpire behind home plate. So a pitch on the left side of the graph (and has "negative horizontal movement") moves in on righties and away from lefties. A pitch on the right side of the graph moves in on lefites and away from righties.

Legend for this Graph and All Subsequent Graphs:
Four-Seam Fastballs = Red Dots
Two-Seam Fastballs = Orange Dots
Change Ups = Dark Yellow Dots
Sliders = Blue Dots
Curveballs = Purple Dots

Pitch Type Number Thrown Average MPH Average Horizontal Movement Average Vertical Movement
Changeup 33 86.7 -8.62 +5.96
Curveball 71 77.5 +5.42 -7.19
Four-Seam Fastball
533 94.5 -4.88 +8.26
Two-Seam Fastball
119 94.5 -7.89 +7.45
Slider 125 87.6 +0.44 +1.80

Table 1: The Average Movement on Wheeler's Pitches. To read, see the legend for the Graphs above.

For the most part, Wheeler's pitches have retained basically the same movements/velocity as we saw in his first start. Both of his fastballs average 94.5 MPH, with his four-seamer with little tail and without a lot of "rise," his two-seamer doesn't sink but has a little amount of tail. Again, as I noted in the first post on Wheeler, neither of these fastball should dominate due to movement, but will have to do so via velocity (obviously plus) and location.

Wheeler's secondary offerings start with a slider which has similar movement to Matt Harvey's (and Mejia's) - it doesn't have great movement, but it has fine movement relative to Wheeler's fastball and comes in at a good velocity (not as good as Harvey's of course). Then there's his curveball, which is very different from Harvey's in that it has a sweeping 11-5 action (lots of movement away from right-handed batters and down), but at a lower velocity (under 80 MPH for the most part). Finally, Wheeler has a change-up that he brings out on occasion against left-handed batters, with a little more tail and sink (but not that much) than his two-seamer at around 8 MPH slower.

Again, nothing has changed with these pitches' movements from Wheeler's first start.* But whereas before we could only look at the movement and velocity of these pitches and speculate as to the results, now we can actualy look at the results of these pitches. So let's do so.

*It does look on the graph like Wheeler might have two curveballs, one with more sweeping action and one a little more slurvish, but most of those showed up in one start and I'm not convinced those weren't classification errors.

Wheeler's Pitch Usage:


Figure 3: Wheeler's Pitch Usage against each type of batters.

As you can see, Wheeler relies heavily on his fastballs against both types of batters. But nowhere is that more apparent than against lefties: 77.4% of his pitches against Lefties are fastballs, with most of these being four-seamers. Against Righties, Wheeler is slightly more willing to go to his secondary pitches, throwing only 71.4% fastballs, although that's still a ton of fastballs. Overall, Wheeler checks in as #5 among starters in fastball usage. This isn't necessarily problematic - the elite Cardinals' rookie pitcher Shelby Miller is throwing fastballs just slightly less often - but it does essentially mean that Wheeler's fastball needs to be really good to survive.

Wheeler's other pitches are rarely used against left-handed batters, with the curve and change-up representing the majority of his off-speed stuff to lefties. But against righties, Wheeler leans heavily upon his slider - throwing it over 20% of the time. Wheeler's curve is rarely used against righties, while his change-up has been thrown exactly ONCE against these batters, and thus is best ignored.

Wheeler's Four-Seam Fastball:


First: the good. Wheeler gets a swinging strike rate of around 8% against both left and right-handed batters. That's certainly above average - which is around 7% or slightly below - but not by a great amount. Against Right-handed hitters, the pitch also has solid ground ball #s. Moreover, against right-handed batters, Wheeler does get a solid # of pitches in the strike zone.

In short, this is an effective pitch against right-handed batters, although it's not exactly a world-beater. Wheeler will need to either improve this pitch or come up with a separate "out-pitch" to finish off right-handed batters if he wants to take the step toward being an ace, but it's a very solid pitch regardless.

Now the bad: While the whiff rate is above average against left-handed batters too, everything else about the pitch isn't working very well. The pitch is an extreme fly ball pitch so far against left-handed batters (8/40 balls put into play have been on the ground), and more importantly, it's highly inaccurate: Wheeler's Strike Zone rate of 51.45% would put him in the bottom 1/3 of qualified fastballs*

*The number above labeled In-ADJ-Strike-Zone% essentially measures how often the pitches are in the strike zone as the zone is ACTUALLY called - so this adjusts for the different zone given to left-handed batters than right-handed batters.

Moreover, batters simply aren't swinging at the pitch out of the strike zone. Lefties are swinging at only 21% of the pitches of Wheeler out of the strike zone. The end result is that, if Wheeler was to qualify, his rate of having his fastball against lefties called for a ball - over 40% - would be one of the worst in the Majors. This is a major problem, and the root cause of his walks against left-handed batters.

Now perhaps some of this was him tipping his pitches, though I'm not convinced of that given how batters should be expecting fastball from Wheeler anyhow - especially if they are lefties. Of course, if part of it is that batters can recognize the fastball, perhaps Wheeler can fix the pitch just by throwing other pitches more often.

Wheeler's Two-Seam Fastball:


Now we start getting into small sample sizes. For example, I'd suspect when all is said and done, Wheeler's two-seam fastball won't have a lower GB rate than his four-seamer, given that it has similar velocity and more sink (albeit not by THAT much).

On the other hand, it's plausible for the two-seamer to have more whiffs than the four-seamers against right-handed batters, and less against left-handed batters: these are pretty typical splits for a two-seamer, which is usually more effective against same-handed batters.

You'll note again, like the four-seam fastball, Wheeler has had issues getting strikes with the two-seamer against lefties, this despite the fact his accuracy against lefties is the same as against righties. Again, batters not swinging at pitches out of the zone is the root cause here.

Wheeler's Slider


Wheeler's slider is his primary offspeed pitch against right-handed batters, and is essentially his "out pitch" - although again Wheeler still throws more fastballs than anything with 2 strikes (although it's close on 0-2). And thankfully it gets more whiffs than his fastball.

The thing is that that shouldn't be a surprise - it's a breaking pitch that's more often thrown out of the zone, it SHOULD get more whiffs than the fastball. And while a swinging strike rate of 12.84% isn't BAD, it's not good either - it's actually BELOW AVERAGE for a slider. The pitch hasn't been a great pitch at getting grounders either.

Now a slider with this movement/velocity can do better than this, especially as played off the fastball. Wheeler doesn't have Harvey's slider - again the movement is similar but the velocity is a bit lower - but the pitch should be more effective than this.

Wheeler's Curveball


Wheeler's other breaking ball is his curve but it's thrown quite a bit less than the slider, giving us only a small sample size of data to work with. The curve has been the primary off speed pitch against lefties for Wheeler - it was again in his 10th start - but that isn't saying much.

Again, against lefties, the pitch hasn't been good so far, though our sample size is far too small to be even close to predictive. It's been taken for a ball a ton of the time (barely any swings), but lefties have whiffed on 50% of curves swung at, so the swinging strike rate is actually above average for a curveball, although not great. That said, it hasn't been a successful pitch.

Against righties the curve has actually been better than the slider, but well, tiny sample size.

Wheeler's Change-Up


When a pitcher uses a slider as the primary off-speed pitch against same-handed batters, it's very common, if not most common, for the pitcher to use a change-up as the primary off-speed pitch against opposite-handed batters. For Wheeler, that's not the case: he's thrown more curves than change-ups to Lefties (and no change-ups in his 10th start)

Again, tiny sample size warning. But again, the pitch hasn't been truly effective, with a swinging strike rate below average for a change-up. Still, you'd think Wheeler would want to throw this pitch more often given his issues with lefties.


I need to separate out my words about Wheeler above into two categories.

First, for Wheeler to be a solid Major League pitcher, the main thing he needs is to increase his control, particularly against lefties. This is fairly obvious - and the key is better location on the fastball to left-handed batters.

That said, part of the problem is that left-handed batters simply aren't swinging much when the ball is out of the zone, so Wheeler needs to do something to fix that. I wonder if mixing in more pitches could help, but the solution to this is something that isn't apparent to me and is what actual scouts/the team coaches are for.

Second, for Wheeler to be an ace, his results on at least one of his off-speed offerings needs to improve substantially. Right now, Wheeler is basically going entirely off his fastball. In fact, as Dan Brooks noted on twitter, Wheeler's gone even MORE fastball-heavy as the season has gone on.

The problem is that while Wheeler's fastball is good, it's not like Harvey's yet - it isn't getting a ton of whiffs (it's above average but slightly). So unless Wheeler is going to drastically improve it - and other than control I doubt it that much given that it's already considered his best and most developed pitch - he needs to find an offspeed pitch he can trust to get whiffs.

Again, we shouldn't expect Harvey level strikeout #s from Wheeler - that's an incredible amount to expect of anyone. But expecting K/9s closer to 9 than 7 shouldn't be unreasonable for a prospect of Wheeler's pedigree with his velocity, and to do that he needs to find some off speed offerings he can work in to his repertoire and use them effectively.

A quick Reminder: Matt Harvey threw a ton of fastballs last year (66%), even if not to the extent of Wheeler, ,only to drop his fastball usage dramatically this year. So perhaps that's the plan for Wheeler as well, to work in the off-speed stuff after a half season in the bigs. That said, Wheeler's offspeed stuff is miles behind where Harvey's was last year, so there's a good deal of work to go on that front.

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