Marco Gonzales is Quietly (Re)Learning the Art of the Breaking Ball

The development of Marco Gonzales is essential for the Seattle Mariners immediate or long-term pitching success, insight into the very way the Mariners construct their starting rotation. Gonzales is another pitcher with long-term control (through 2023) that Jerry Dipoto found in a myriad of whimsically addictive trading, acquired in July 2017 from the St. Louis Cardinals in exchange for right-field prospect Tyler O’Neill. Tommy John surgery history and analytics pushed him immediately into the safety net of the Mariners AAA affiliate, the Tacoma Rainers, with the delineation of ‘long-term’ project. However, injuries to anyone in a Mariner uniform ensured no AAA project was safe in Tacoma; Gonzales received his callup on August 5, 2017, never to look back.

Gonzales just finished the months of June and July with the Mariners second most innings pitched (59.2, just behind Mike Leake’s 62.1 innings) and a FanGraphs’ WAR of 1.3. If arguments were to be succinct by WAR, then Gonzales has been the second most stable starting Mariners pitcher with 2.5 WAR on the season after 119.2 innings pitched. The stability of Gonzales, however, is entirely despite allowing an above average BABIP and contact percentage of .305 and 80.2, respectively.

Gonzales, by design, is a breaking-ball pitcher who seeks contact, but that does not make his games any less tedious or uncomfortable. If there were an analytic for uncomfortable pitching style, where the clean-up process becomes essential, Gonzales would top that leaderboard. Context is essential to introducing his development for two-fold reason. First, Gonzales is tied to the Mariners front office vision; a pitcher that they have buried plenty of faith in his steady increase in workload around their style of development. Second, this is not a regular development process akin to the league standard; Gonzales was thrown into the MLB due to the Mariners haunting injuries through 2017, and thus has been forced to re-learn the art of the breaking ball ahead of schedule.

The Mariners noticeably began to have an immediate effect on assisting Gonzales tap into his development as a breaking-ball pitcher. His four-seam fastball was still utilized 52.5 percent of the time last season but steadily dropped throughout his August and September in Seattle. At the same time, he began to utilize his curveball, doubling the rate which he used with the Cardinals to 16.7 percent, while also slightly increasing his changeup.

There was a vision in-tact, and in 2018, that vision came to fruition. His four-seam fastball fell to 10.9 percent with a cutter and sinker appearing at the rates of 18.6 and 23.7 percent, respectively. His curve-ball further rose, effectively tying together a breaking ball type of arsenal with the sinker, changeup, and curve of equal use dependent on the situation.

This is more than a natural change to strategy, but a compelling point that Gonzales had finally overcome Tommy John surgery. He had dropped his cutter and sinker earlier in his career to alleviate torque and recover safely. Reports and commentary from catcher Mike Zunino earlier in the year signaled that this season would see a new, more aggressive Gonzales attempting to conform batters, not he conforming to batters.

Confidence from Gonzales is seen in an addiction in committing to the quickened recovery pace. Over the span of the season, the evidence already points toward Gonzales finding a natural flow to his post-Tommy John arsenal and his goal of using the zone’s shadow to pinpoint strike percentage. Further breakdown shows two important developments. First, he is using less of the zone to derive more swings, particularly outside-swing percentage. Hence, he no longer needs to use in-zone pitches to deceive batters into soft-contact on outside pitches, he can just use his natural breaking pitch. Second, at the same time, he is maintaining an uncomfortable contact percentage and BABIP rate, both are controlled with BABIP trending down on the season.

Breaking-ball pitchers are going to be more brazen in their attempt to get outs based on soft-contact, but Gonzales is showing an ability to decrease his BABIP rate on the season while also stabilizing his FIP and xFIP around 3.3 and 3.4, respectively. The stabilization of Gonzales, again, is equally impressive for how quick he has turned around, albeit, a bit surprising because of how uncomfortable his BABIP is.

Gonzales’ batting average, slugging, and ISO rates per zone are higher than average, hence the above average BABIP. His expected batting average is either similar to or the same as his functional output, but his expected slugging and ISO become worrisome, leading to the analytical insight that any moment could lead to a sudden regression.

The summary point on Gonzales’ analytics would debate the point regression is inevitable; his overwhelming confidence and ability to control the quality of contact is what makes Gonzales development as a pitcher enticing. He has maintained a steady bought of keeping launch-angle to nine degrees while holding barrel percentage to six all for the goal of making balls hit into play, easier to handle. Perfection from Gonzales may never be expected, or reasonable – his changeup floating in the upper zone to set up a low curveball does provide dangerous contact opportunity; the magic, however, in his arsenal is the crisp preciseness to obtain quick outs and double-plays if the bases are loaded. Between the sinker and curveball follow-up, spotting adequate contact on Gonzales is epitomized by the random chance of baseball.

On that note, Gonzales’ pitching style might be summarized as an ability to double-down on batting randomization.