The Wily Peralta That We’ve Been Waiting For

On June 12th of this season, the Milwaukee Brewers optioned Wily Peralta to AAA Colorado Springs. The one-time top prospect and “former 17 game winner” was arguably the worst starter in the big leagues at that time, having worked to a 6.68 ERA and 42:27 K/BB ratio through 66.0 innings while barely averaging 5.0 innings per start. Peralta had been bad in the big leagues for two straight years (4.72 ERA, 1.62 K/BB ratio in 2015) and wasn’t much better at preventing runs in Colorado Springs, where he posted a 6.31 ERA in 41.1 innings.

On August 9th, Peralta returned to Milwaukee to take the place of the injured Junior Guerra in the starting rotation. The loss of the club’s unquestioned ace this season left big shoes for Peralta to try and fill, and expectations were obviously minimal based on his work from earlier this season.

It quite surprising, then, to see how Wily has thrived since being recalled to the majors. Over five starts and an even 30.0 innings, he’s posted a 3.00 ERA with 27 strikeouts against just 10 walks. So what’s changed to help drive Peralta’s success?

First off, Wily’s throwing harder. Per Brooks Baseball, his four-seam fastball averaged 95.40 MPH during his first 13 MLB starts this year. Since being recalled, however, his average fastball velocity has jumped up to 96.47 MPH with a max of 99 MPH, numbers that he hasn’t approached since his strong 2014 campaign.

Second, he’s been locating his pitches much more effectively. During the first half of the season, Peralta had difficulty keeping both his four-seamer and his sinker out of the middle of the strike zone.

As a result, batters were teeing off against his hard stuff to the tune of a .325 average with three homers against his four-seamer and a .382 average with five long balls against his sinker. He’s been much better at keeping his hard stuff on the edges of the zone in the second half of the season:

Predictably, the better location has lead to batters being less effective against his fastball variations. Wily has seen a 64 point drop in his four-seam BAA and a 96 point drop in sinker BAA, with just two home runs allowed on his sinker.

Wily’s slider has been different the second time around, too. Early on this year Peralta’s slider was averaging nearly 86 MPH with 1.18 inches of horizontal break and 1.99 inches of vertical break. He’s slightly increased his usage during the second half (29% to 32%) and took about a mile and a half per hour off of the average velocity, down to 84.54 MPH, giving it greater velocity separation from his high-octane fastball. He has simultaneously tightened up the break, as well, to 1.01 horizontal inches and 0.85 vertical inches while slightly varying the locations that he’s thrown it to. Compare his slider usage during the first half:

And since being recalled:

The slider has long been considered Peralta’s “out” pitch, but it gave batters little trouble during the first half of the season as they batted .316 with three homers against the offering. In the second half, Peralta has more than doubled the whiff rate on his slider (9.80% to 21.52%) and batters are hitting just .125 against the pitch. 17 of the 27 strikeouts that Peralta has recorded have come against his breaking ball.

Speaking of whiffs, the strikeouts that we expect to see from a pitcher who throws in the upper-90s have finally shown up for Big Wily. He struck out a putrid 12.3% of opposing batters during his disappointing 2015 campaign and though that improved to 13.6% during the season’s first half, that’s still well below the league average. A pitcher simply can’t expect to give up that much contact and consistently keep runs off the board, especially with Milwaukee’s defense behind him.

Over his last five starts, however, Peralta’s K-rate has jumped up considerably to 22.9%, which is comfortably above the league average of 21% and would be far and away the best total of any season during his big league career. He’s nearly doubled his swinging strike percentage (6.6% to 10.8%) and has seen a marked increase on his pitches at swing out of the zone (24.5% to 34.6%). Swings against Peralta have increased (43% to 45.2%) while contact has decreased significantly (84.7% to 76.0%), and more strikeouts have naturally followed.

On the contact Peralta has given up, he’s seen a nice decrease in hard contact (36.4% to 33.3%) along with a simultaneous increase in soft contact (15.3% to 19.8%) and has done a better job at keeping the ball on the ground (49.1% to 51.3%). He’s seen his BABIP drop more than 100 points down to .260 and his WHIP from 1.88 to 1.13. He’s cut his walk rate by more than half a batter per nine innings, too (3.68 BB/9 to 3.00).

All of these improvements come with the caveat of a small 30 inning sample size of course, but they are encouraging nonetheless. This finally looks like the Wily Peralta that we’ve been waiting for: the capable mid-rotation starter that he was thought to be coming up through the minor leagues. Peralta has gone from a borderline non-tender candidate to likely earning himself a spot in the rotation for next season. If he can sustain these improvements going forward it will bode very well for Milwaukee, whether Peralta becomes a trade candidate or a member of the next competing starting rotation.

Statistics courtesy of Fangraphs and Brooks Baseball