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Everyone can’t stop looking at Marco Gonzales

What’s real and what’s a mirage in Marco Gonzales’ first five starts?

MLB: Seattle Mariners at San Francisco Giants Neville E. Guard-USA TODAY Sports

Marco Gonzales fascinates me. My phone contains an ever-growing list of potential article ideas, but I find myself spurred to return to Gonzales. Few pitchers with Gonzales’ lack of track record have been given as dramatic votes of confidence as Jerry Dipoto’s front office have done with Marco this year. Gonzales has thus far delivered peripherals that at first glance suggest that faith was well-placed, but it’s not quite that simple. He may well be a superior pitcher, but if so, it’s because he’s doing things drastically differently than ever before.

Before we get into Gonzales’ pitch mix, we’ll start with his results. An FIP of 2.61, an ERA of 4.37. A K/9 of 10.72 and a BB/9 of 1.59. A BABIP against of .406. Some of those marks are among the league’s best for qualified starters - by FIP he’s 15th in MLB, by K/9 he’s 21st. Even better, Gonzales has allowed a downright unfair BABIP of .406 that is the second-highest by any starter so far this year. In an ideal world, that BABIP would drop to a more normal rate as the rest of his peripherals remained in place.

The trouble is Marco hasn’t just been unlucky. It’s one thing to allow hits consistently off bloopers, but with just shy of 40% of his his contact allowed being “Hard,” hitters seem to be earning their contact. Statcast’s xwOBA seems to agree that Gonzales is about where he should be, noting little difference between the contact he’s given up and what would be expected from it. The hits haven’t been cheap, and while the BABIP may drop from a few extra outs and his strand rate may improve from a ghastly 62.9%, Marco is flirting with homer-based disaster if that hard contact occurs on a few more fly balls.

So Marco’s probably not been as unlucky as he looks, but what about that dazzling K/9? 10.72 is Paxton-esque, and seeing Gonzales slotted in ahead of Clayton Kershaw on almost any leaderboard brings a smile to my face. But that BABIP did more than disrupt Marco’s ERA; it meant he’s seen plenty of batters in a few starts without recording outs rapidly. That’s why we should always trust K% over K/9.


It’s not a dramatic drop - 21st to 25th, but it gives us a better sense of how often Marco is actually striking people out. More notably, not all strikeouts are made equal. The most common way major league hitters strike out is swinging, and, logically, a high swinging strike rate is a good indicator of a high K%. But... not for Marco.

League-average SwStr% for starters is 10.1%

Unlike nearly everyone else, Marco has so far amassed elite strikeout totals despite a below-average swinging strike rate. It’s not impossible, of course, as we see known Good Pitcher Carlos Martinez doing something similar, but it’s tough. Last year, José Quintana and Trevor Bauer were the lone starters to earn K% over 26% with sub-10% swinging strike rates.

When it comes to strike threes, the effect has been especially pronounced. 37.0% of Marco’s K’s have been looking. I don’t imagine “percentage of strikeouts that were looking” is a number most of us have a framework for, so let me just tell you that 37% is quite high, and that 23.5% is league-average. While Marco sits only 25th-highest in MLB so far this year, he’d have had the 8th-highest season-long total of 2017 with his work so far this year. When perusing these leaderboards, I was left with a nagging curiosity.

Many of the names are familiar - Carlos Martinez, Trevor Bauer, José Quintana, and others who posted above-average K%, despite low SwStr%, appear high on the Backwards K leaderboards for 2017. That’s not revelatory; those pitchers had to get their strikeouts somehow. But that many of the same pitchers appear again near the top of this year’s K% & Backwards K leaderboards despite unassuming SwStr% numbers suggests that earning an extra number of strikeouts looking could be a specific skill. At the very least, it could be tilted towards those with a certain skill set.

But what is a skill set that results in a high rate of hitters striking out looking without causing them to swing and miss at other points in time?

Based on what Marco Gonzales is doing differently than ever before, I believe it’s connected to his unpredictable sequencing. Much like several of the pitchers featured on the lists where he now finds himself, Marco has diversified his slate of offerings to the point where hitters are unable to expect any particular pitch. Gonzales has thrown five types of pitches so far this year:

Marco Gonzales Pitch Usage

Type of Pitch Percentage Use
Type of Pitch Percentage Use
Sinker 23.30%
Four-seam 21.80%
Cutter 13.90%
Change-up 23%
Curveball 17.80%

As Marc W at USSM noted earlier this week, Gonzales has utilized his new cutter in particular to throw hitters off-balance. In two-strike counts, Gonzales has been similarly even-handed:

Brooks Baseball

That diversity of usage in two-strike counts in particular seems liable to aid Gonzales in surprising hitters for strike three. He won’t always have as friendly a zone as he had this week against the White Sox, but in lieu of a single dominant strikeout pitch, Gonzales appears to be raising the effectiveness of all his offerings with a varied approach. He’s also done an exceptional job of maintaining a consistent release point with his four-seam, sinker, and cutter, which, by Baseball Prospectus’ pitch tunneling data, has made those three pitches far more effective than their velocity and movement might initially suggest.

It’s difficult to know how long Gonzales can continue striking hitters out at this pace, in this way, but my guess is he falls back to Earth to some degree. However, as long as he maintains his strong control with his pitches, he’ll have an opportunity to improve his ERA, even as his FIP may slip somewhat. Then again, if Marco can sustain this strikeout rate and sees his BABIP normalize anyways, Seattle will have stumbled upon a second ace. More likely, they at least hopefully have a decent guy to join Mike Leake in the middle of the rotation. That’d still be plenty.