Marco Gonzales, the new Mariners ace

Marco Gonzalez has earned the Opening Day start in Tokyo, Japan after an effective 2018 season. Without James Paxton on the roster, that leaves the 27-year old as the club’s ace.

Gonzales is coming off of a season where he pitched 4.00/3.43/3.59 in 166.2 innings (the most of his career). His effectiveness came from his surprising ability to strikeout batters last year; 21.1% of batters faced in 2018, vs. 17.3% in ’17 and 6.3% in ’15 during stints majors. There is reason to believe that the 27-year old is going to be able to sustain this strikeout rate as it matches what he was able to do as a starter in the minors.

What’s interesting is that Gonzales, unlike Félix Hernandez, appears to have bought into analytics. The third-year veteran has used his off speed stuff more than his fastball because they’ve been more effective.

Last season, the starter only threw his fastball on 32.7% of pitches, compared to 52.5% in ’17 and 57.5% in ’14 — those are the other years he saw significant innings as a starter with the major league club. Even with the decreased usage, hitters still had a batting average of .283 and a wRC+ of 151 last year against the fastball. Gonzales was also unable to induce swings at his fastball when he threw it outside of the strike zone.

As his fastball use has decreased, his curveball (22.3%) and sinker (23.4%) more. The curveball has generated more swings outside of the strike zone (39.9%), and a lower batting average and wRC+ than his sinker; batters hit .322 with a wRC+ of 170 off his sinker, while they hit .305 with a wRC+ of 103. His curveball, impressively, rarely led to walks last season (0.6% of batters walked earned ball four on this pitch); while he had a strikeout rate of 14.9% on it.

What made his curveball dangerous, despite the relatively high batting average against it, was the fact that it induced a boatload of ground balls last season. Unfortunately for Gonzales, he had a lot of bad luck with the curveball as opposing teams had a BABIP of .343 against it last season — that’s 28 points higher than it was in 2017; if that BABIP returns more to where it was in 2017, his curveball is going to be an effective pitch that he can rely on.

Gonzales’ sinker also had a high BABIP against, at .349; but batters were more likely to square up his sinker than his curveball as they recorded an isolated slugging percentage of .161 against it — the curveball had a ridiculously low ISO of .091.

His most effective pitch last season was his cutter. Batters had trouble figuring out the pitch as they only hit .223 with a wRC+ of 89. The cutter also induced the second most swings outside of the strike zone; opponents swung at 36.6% of cutters out of the zone.  Gonzales also effectively used his cutter to put batters away as 31.7% of his strikeouts came on it.

The pitch I’d like to see him use more is his slider. Gonzales has only used his slider sparingly, in the majors, in two seasons (2014 and 2018) and the opposing batters have hit .250 against it with a wRC+ of 82 in both seasons. If he can increase his usage of this pitch more, I think it would make him even more effective on the mound. Now he doesn’t need to completely rely on this pitch, but if he can mix it in a little more…I could see it making a dramatic difference for him.

Heading into this season, Gonzales has earned the title of ace by buying into analytics and using his off speed stuff more; and it led to much more effective results for the kid that attended Gonzaga in 2018. If he can keep up the development of his breaking balls, he could be in for one hell of a 2019 season.