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Examining David Peralta’s confusing projections

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The Arizona outfielder followed up his breakout 2015 with an injury-riddled 2016. What will 2017 bring?

MLB: Miami Marlins at Arizona Diamondbacks
With a healthy wrist, Peralta should continue to watch his home runs fly in 2017.
Matt Kartozian-USA TODAY Sports

For the third straight offseason, BtBS is looking at players where the projections disagree. Check out all the entries here.

Welcome back to Mediating Projections! This week, we’re taking a look at David Peralta. The 29-year-old Diamondbacks outfielder broke out in 2015, hitting .312/.371/.522 and earning 3.7 fWAR over just 517 plate appearances. But injuries took a toll on his performance in 2016, as he limped his way to a .251/.295/.433 triple-slash and 0.3 fWAR in 183 plate appearances.

Regarding 2017, both ZiPS and Steamer don’t expect Peralta to regain his 2015 production, or to play as poorly as he did in 2016. Yet neither is sure of precisely how well he’ll fare:

Peralta projections

System PA BB% K% ISO BABIP AVG OBP SLG wOBA wRC+ Fld fWAR fWAR/600
System PA BB% K% ISO BABIP AVG OBP SLG wOBA wRC+ Fld fWAR fWAR/600
ZiPS 413 7.5% 19.9% .195 .335 .286 .344 .481 .352 118* -1.0 1.9 2.8
Steamer 536 6.8% 20.4% .173 .321 .273 .327 .446 .330 99 -1.9 0.9 1.0
*This is OPS+, as ZiPS doesn’t project wRC+; the difference should be minimal. Data via FanGraphs

Where will Peralta’s winding career head this season? Since both systems project similar fielding numbers, we won’t need to analyze that. For this edition, we’ll examine the four areas of disagreement — walks, strikeouts, ISO, and BABIP — and come to a conclusion about which projected outcome is correct.

Walks — 7.5 percent (ZiPS) vs. 6.8 percent (Steamer)

Peralta’s not an especially patient player. Over his two-odd years in the Arizona minor-league system, he walked in 6.5 percent of his 489 trips to the dish. He managed to improve considerably upon that in 2015 — when he took a free pass 8.5 percent of the time — but come 2016, he’d regressed to a 4.4 percent walk rate. While both Steamer and ZiPS think he’ll bounce back from there, they’re not sure about how much he’ll do so.

The pertinent question, here: Why did Peralta’s walk rate drop off in 2016? Well, he started swinging more often, at pretty much everything:

Image via

Pitches inside the strike zone? He offered at those 70.5 percent of the time, up from 65.9 percent in 2015. Pitches outside the strike zone? He chased those 36.6 percent of the time, up from 33.5 percent in 2015. Up, down, away, in — Peralta became more aggressive all-around last year.

What that means for his strikeout rate, we’ll discuss in a moment. In terms of walks, this has an obvious consequence: more swings = fewer balls = fewer bases on balls. Indeed, Peralta’s strike rate soared from 63.3 percent in 2015 to 66.7 percent in 2016. Pitchers did start throwing more pitches in the strike zone against him — likely because of the declines in power and average, which we’ll delve into momentarily — but his swing-happy approach was what did him in.

Peralta’s bellicose approach in 2016 could prove to be short-lived; if he pressed at the plate due to his injury, he might return to the relative patience from 2015. If he doesn’t, though — if Peralta is the new Pablo Sandoval — then the free passes are gone for good. Either way, what Steamer projects makes a little more sense here.

Strikeouts — 19.9 percent (ZiPS) vs. 20.4 percent (Steamer)

Peralta was something of a contact hitter as a farmhand, going down on strikes in 11.2 percent of his plate appearances. That ability didn’t translate to the Show, where he struck out 20.7 percent of the time in 2015 and 23.0 percent of the time in 2016. Here, as with walks, he projections are fairly close yet still diverge by a little bit. If Peralta’s strikeout rate does dip, how low will it go?

As noted previously, Peralta started to hack in 2016, perhaps due to his numerous health-related woes. That didn’t cause his contact rate to suffer, though — in fact, he actually made more contact last year, especially on pitches in the strike zone:

Image via

Thanks to his improvement in that regard, Peralta’s 2016 whiff rate (10.8 percent) was in line with his 2015 whiff rate (10.6 percent). And with the increased Z-Swing rate came a decreased called strike rate — from 15.6 percent in his breakout year to 14.5 percent in his follow-up.

If Peralta had the same amount of swinging strikes, and even fewer looking strikes, where did all those extra strikeouts come from? The jump in strike rate meant Peralta found himself in more two-strike counts — last season, 31.2 percent of all the pitches he saw came with two strikes, a slight uptick from 29.1 percent the year before.

The high strike rate notwithstanding, there’s reason for optimism here. Peralta has something of an Adam Jones-esque profile — swing at everything, and make enough contact to stave off strikeouts. While the two systems don’t diverge by much, the steady whiff rate, together with the plunge in called strikes, makes me side with ZiPS.

ISO — .195 (ZiPS) vs. .173 (Steamer)

Peralta’s game never revolved around walks or strikeouts. Even in 2015, his plate discipline was pretty pedestrian. Rather, he set himself apart with his power — only 27 other hitters had a better ISO than his .210. That plummeted to .181 in 2016; from there, he could either improve (as ZiPS predicts) or continue to get worse (as Steamer foresees). What’s the future of Peralta’s power?

The major issue plaguing Peralta in 2016 was a wrist injury, originally inflicted in the final week of the 2015 season. He strained it and went on the DL in May, came back the following month, re-injured it in August, and thereafter underwent season-ending surgery. In September, the Arizona Republic’s Nick Piecoro outlined the problems the injury caused:

Even when outfielder David Peralta was healthy enough to play this year, he wasn’t the hitter of the past two seasons. He expects that to change next year following last month’s wrist surgery.

“You use your hands to hit,” Peralta said. “If something is wrong with your hands, it’s impossible to execute.”

Peralta bent his right wrist awkwardly trying to make a lunging catch at the end of the 2015 season, and though it did not appear he needed surgery at the time, he says the irritation he felt in his wrist for much of this year was related to that injury.

Here’s the thing, though. During his 2015 breakout, Peralta usually smoked the ball when he put it in the air — his 50.3 percent hard-hit rate ranked him in the 94th percentile. Because of that, he had a .548 ISO on air balls, which put him in the 93rd percentile. Then last year, he dropped to the 72nd percentile in air ISO (.444), despite remaining in the 89th percentile in hard contact (50.0 percent). His overall rate of air balls also increased, from 47.9 percent in 2015 to 49.2 percent in 2016.

What does all that mean? Peralta should be healthy in 2017: He finally underwent surgery, and later on in that Piecoro piece, he said “everything is good right now” with regards to his wrist. But the wrist ailment didn’t appear to hurt his power last season; the trouble stemmed from bad luck. He still made plenty of solid contact — it just didn’t go over the fence, or fall in between outfielders.

Of course, it’s entirely possible — nay, probable — that good fortune benefited Peralta in 2015, just as misfortune hurt him in 2016. During his breakout campaign, he led the Senior Circuit with 10 triples, a rather capricious outcome that won’t always stick around. Still, the fact that he kept getting good wood gives me hope, such that ZiPS’s bullish forecast wins out here.

BABIP —.335 (ZiPS) vs. .321 (Steamer)

BABIP really helped Peralta’s cause in 2015 — where his aforementioned ISO slotted him 28th in the majors, his .368 BABIP placed him in the top 10. Then came 2016, when he nosedived (nosedove?) to a more mediocre .310 BABIP. Getting as many hits as he did in 2015 was lucky, without a doubt; still, it’s worth wondering how much he’ll rebound from his 2016 decline.

While we just spent a lot of time sorting through Peralta’s air balls, he hits a disproportionately large amount of grounders: His ground ball rate was 52.1 percent in 2015 and 50.8 percent in 2016. In the former year, his .271 grounder BABIP put him in the 79th percentile; in the latter, his .211 BABIP put him in the 39th percentile. His air ball BABIP didn’t decline nearly as heavily — the ground balls were what sunk Peralta in 2016.

This is where the wrist injury enters the equation. In terms of ground-ball hard-hit rate, Peralta went from the 82nd percentile (21.8 percent) to the 43rd percentile (19.7 percent). Part of that was other hitters getting stronger around him — from 2015 to 2016, the MLB-wide hard contact rate for grounders spiked by more than three percentage points — but beyond that, Peralta just had trouble squaring the ball up.

If Peralta’s wrist stays intact, he could regain the solid grounders from a year ago. Then again, since Peralta’s a left-handed hitter who doesn’t go the opposite way very often, he has another thing working against him: the dreaded shift. 57.1 percent of his balls in play last year came with the shift on, up from 41.4 percent the year before. Based on how much the shift has exploded in popularity recently — from 2013 to 2016, it increased fourfold — I’d expect that trend to persist.

Peralta has decent speed (remember, 10 triples), so he can always leg out an infield hit or two. That probably won’t be enough, however, to make up for the shift, or for all the weak grounders that are fielded cleanly. I’m confident in Peralta’s power-hitting ability, but when it comes to average, Steamer’s pessimism takes the cake.


The final tally: two victories for Steamer, and two for ZiPS. This year, Peralta should regain his power stroke and cut down on his strikeouts, while seeing moderate upticks in his walk rate and BABIP. That would make him, over 600 plate appearances, about a two-win player — far from the level he was at two years ago, yet still a respectable output. For a guy who took the Rick Ankiel path, we can chalk anything better than replacement level up as a win.


Ryan Romano is the co-managing editor for Beyond the Box Score. He also writes about the Orioles for Camden Depot, sometimes. Follow him on Twitter if you enjoy angry tweets about Maryland sports.