Robert Gsellman must rediscover the magic

This past Wednesday, Robert Gsellman made his first start since the May 13th stinker that finally prompted the Mets to skip his next start and use him out of the bullpen. He threw six innings of six-hit ball while giving up three earned runs and striking out three. Although it was against one of the worst offenses in baseball, it was a positive sign for a pitcher struggling mightily to follow-up a fantastic 2016 debut where he seemingly came out of nowhere.

It was his best start since his outing against the Phillies on April 19th when it looked as though he was getting his season on track. Unfortunately, the wheels came off shortly thereafter and he hasn’t come close to resembling the surprising revelation he was for the Mets last season.

He now sits at 44.2 IP for the season, the exact number of innings he pitched last year. The results couldn’t be more disparate, however. Take a look at the table below for some comparisons.

2016 44.2 8.46 3.02 .325 81.3 % 3.6 % 2.42 1.28 2.63 3.38
2017 44.2 6.65 3.02 .355 56.3 % 13.5 % 6.45 1.66 4.29 4.25

There are four things that clearly stand out here: his strikeout rate, his home run rate, his FIP, and his left on base percentage. Interestingly, and when we take into account his other periphery stats, these all kind of tie into each other when explaining the poor results. The largest swing in the above table is in his LOB%, which went from an excellent 81.3% in 2016 to a devastatingly poor 56.3% so far this year. This is particularly interesting because our Mets360 projection for Gsellman included LOB% as something to keep an eye on this season. His 2016 LOB% didn’t reflect his typical minor league numbers, so it was a valid data point to keep in mind.

Why such a dramatic swing? His lower strikeout rate is a partial explanation, obviously, but the more telling stat above is his HR/FB ratio. Now, he’s not giving up more fly balls this season. In fact, his GB%, LD%, and FB% are all very similar to last season. The problem is that more of those fly balls are going out of the park for home runs. Did you notice the difference between his 2016 FIP and xFIP? The xFIP stat replaces a pitcher’s home run total with how many they should have given up based on their fly ball rate (among other factors). As we can see this year, his FIP now more closely resembles his xFIP as those fly balls turn into homers. In addition to home runs, he’s simply given up hits at a higher rate than he was last year, despite walking the exact same number of batters.

Hitters clearly have a better read on him this year, leading to worse results. What’s the root cause of this, though? The answer to that question goes beyond the scope of this article, but we can quickly note two things. First, the average velocity on each of his pitches is mostly similar, though there is a slight dip in them save his slider (which has actually gone up a tad). Second, and most telling, the Pitch/FX values on his pitches have nosedived this year. This is especially true for his fastballs and slider. The higher overall contact percentages against him in 2017 bear this out.

We’re left to ponder a few things as we watch Gsellman struggle to capture the magic of his debut. Was last year an anomaly stemming from a league unfamiliar with him? Is this year simply a sophomore slump? Based on the noticeable decline in his “stuff” this year, I’d wager the issue is either mechanical or medical. The latter would be a gut punch, given what we’ve already seen this season with the team’s health. The former at least leaves hope that whatever is ailing him can theoretically be corrected. We’ll know more as the season progresses, but one thing is clear: the Mets need Gsellman to rediscover whatever it was that propelled him into multiple top prospect lists this offseason if they hope to stand a chance.

2 comments for “Robert Gsellman must rediscover the magic

  1. May 27, 2017 at 8:47 am

    I enjoyed this piece.

    My belief is that what’s doing Gsellman in this year is command. While the BB rate is identical to last year, those pitches don’t seem to have the same placement as a year ago.

    You mentioned HR/FB rate but it goes beyond that. Anytime the batter gets the ball off the ground, he seems to do great damage. Gsellman has a lower LD% than last year but when they hit those LD, they’re doing damage. Opposing hitters have an OPS nearly 300 points higher this year on LD compared to a year ago.

    And with fewer strikeouts, there’s more opportunity to elevate the ball.

  2. John Fox
    May 27, 2017 at 10:46 am

    I tend to think it is not a medical issue with his arm. As mentioned in the article, his fb velocity has not dropped much. I checked it out further, and according to Fangraphs his vFA (4 seam fb) velocity went from 93.7 last year to 93.4 this year and vFT (2 seam) from 93.6 to 93.1 that looks like it is not significant statistically, and if it were an arm issue I think it would show up in velocity. Also the Mets have had so many pitching injuries they would be treating Gsellman with kid gloves if they thought there was any hint of an arm problem.

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