What to expect from Gio Gonzalez

The Milwaukee Brewers made three additions off the waiver trade market on August 31st. Two of those players - Xavier Cedeno and Curtis Granderson - have already had some impactful moments of their own. Later today, the most expensive acquisition of the trio, Gio Gonzalez, will finally get the opportunity to make his team debut when he toes the rubber to start tonight’s game against the Giants.

Gonzalez (who turns 33 later this month) has been one of the top left-handed pitchers in baseball for last decade. Since debuting with the Athletics in back in 2008, Gio has appeared in 308 games and tallied 1,788.2 innings with a 3.71 ERA. He has been an All-Star twice and has two top-6 finishes in Cy Young voting, including last season. The southpaw’s ability to miss bats (8.68 K/9) and induce weak contact has helped thrive throughout his career despite a sometimes troublesome tendency to issues walks (3.77 BB/9). Metrics like FIP- (91) and DRA- (81) view Gonzalez’s overall body of work as well above the league-average, and depending on which WAR metric you favor he’s been valued at between 28 and 34 wins above replacement for his 11-year career.

Unfortunately, Gio hasn’t really approached those types of numbers in 2018. He was a stable source of innings for the Nationals, taking 27 turns in the rotation and tossing 145.2 innings prior to the trade. But in that time, he was able to turn in only a 4.57 ERA. His strikeout rate (7.78 K/9) is the lowest is has been since 2010 while he’s doling out his most free passes (4.32 BB/9) since 2009. The left-hander’s .267 batting average against and 1.531 WHIP are his worst totals since 2009. Gonzalez has never had as much trouble finding the strike zone as he has is 2018 (39.0%, 9th-worst among qualified starters).

There are some reasons to be encouraged by what Gio is bringing to the table, however. His fastball velocity (90.7 MPH) has stayed basically the same as where it was last year, although that was close to a two mile-per-hour drop from his 2016 velo (92.1 MPH). His 9.2% swinging strike rate is up a tick from last season and right in line with his career total (9.4%). Gio is allowing a bit more hard contact than his career average (28.1%), but at 30.6% in 2018, he is still well below the league average. In fact, only 12 qualified starters are allowing hard contact less frequently this year. Gio has limited home runs (0.93 HR/9) and kept the ball on the ground reasonably well (45.5%) in addition to limiting the hard contact, and yet his BABIP against of .319 is 24 points worse than his .295 average over 11 seasons. Gonzalez has been some 11% worse than your run-of-the-mill MLB pitcher this season in terms of ERA-, but when factoring in all the peripheral numbers, estimators like FIP- (104) and DRA- (100) see his work this season as much closer to that of a league-average hurler.

Gonzalez attacks batters with a four-pitch mix, using his four-seam fastball (26.1%), sinker (27.8%), changeup (21.7%), and curveball (20%) at nearly equal rates. Despite diminishing velocity, Gonzalez has turned his fastball into a weapon by frequently using it up in the strike zone, limiting opponents to a .187 average against the pitch and inducing a whiff with it more than 12% of the time. In terms of linear weights, Gio’s biggest problem pitch this season has been his previously plus curveball, which is currently rated as 9.8 runs worse than average in 2018. Right-handed hitters in particular are punishing the pitch to the tune of a .276 average and .172 ISO in 2018.

Considering what the Brewers gave up and that Gonzalez was a waiver-wire acquisition who is a free agent after the season, it seemed like a curious decision at first blush for the org to hold off from committing to him as a starter and wait nine days for his team debut. But perhaps that curveball has something to do with it. According to data from Brooks Baseball, Gonzalez’s release point with his curveball is about three inches higher this season than it was in 2017, when it graded out at +5.8 runs above average. For his career, Gonzalez has averaged 5.59 inches of horizontal movement on his Uncle Charlie, but this season that number is at 7.15 inches. That means more of a “sweeping” shape to the pitch, which would theoretically make it easier for right-handed hitters to pick up out of his hand and subsequently punish. Since joining the team, Gio has thrown a couple of bullpens while working with renowned pitching coach Derek Johnson. If ‘DJ’ could help Gonzalez make the mechanical adjustment that gets his curveball release point back on track, it could go a long way to increasing his effectiveness for the final month of 2018.

Although he hasn’t pitched up to par this season, the Brewers are optimistic that getting dropped into a pennant race and working with Derek Johnson can be the shot in his left arm that Gio Gonzalez needs. He hasn’t been much better lately than Junior Guerra, the man he’s replacing in the rotation, but a lengthy track record of success and some encouraging peripheral numbers help to offer at least a glimmer of hope that Gonzalez can make a positive impact during the four or five starts he should be able to make before the regular season concludes. Those games could very well wind up being the difference down the stretch for the Menomonee Valley Nine as they chase their first postseason berth since 2011.

Statistics courtesy of Baseball-Reference, Fangraphs, Brooks Baseball, and Baseball Prospectus