Wait, Dustin McGowan is good again?

“It’s just there are certain things you’re sure of, like longitude and latitude.” —Sam Seaborn

In the episode of The West Wing that netted Rob Lowe the only Emmy nomination of his career, his character delivers this emotionally charged line at the end of a long week that saw his world turned upside down. Some very important truths in his life turned out to be false. It’s the first thing I thought of when I found out that Dustin McGowan wasn’t bad.

You see, he had been terrible in both 2014 and 2015, and I guess I had just assumed that had continued into 2016. I was wrong. Not only was he not terrible in 2016, he was great! It’s just there are certain things you’re sure of...

Along with this acknowledgement is the tacit admission that I paid zero attention to what McGowan did for the Marlins bullpen last year. Perhaps I was too focused on the baffling brilliance of his teammate Kyle Barraclough, but McGowan’s bounceback happened completely off my radar. Time to make up for that transgression.

First let’s take a look at exactly what kind of year he had statistically, compared to his previous three seasons as a reliever.

It was just 25 innings, but McGowan was fantastic in his first foray into the bullpen with the Blue Jays in 2013. The success wouldn’t last, though, as he saw the wheels fall completely off in 2014 and 2015. In both those years, his strikeout and ground ball rates dropped, and in 2015, albeit in just 23 ¹⁄₃ innings, the walk rate skyrocketed.

Last season, McGowan was able to bring his strikeout rate back up to its 2013 level while improving his ground ball rate to a high previously unseen. Among the pitchers who threw at least 60 innings, he placed in the top 30 by DRA and top 50 by cFIP. Perhaps what’s most remarkable is that he did this with sub-par command and control. Using Baseball Prospectus’ metrics CSAA (Called Strikes Above Average) and CS Prob (Called Strike Probability) we see that McGowan occupied a space all his own.

CSAA is a surrogate for command, as it gauges a pitcher's ability to hit his spots; CS Prob is a surrogate for control, as it shows how many of a pitcher's pitches are in the theoretical strike zone. In this scatter plot of pitchers who threw at least 60 innings, you can see that McGowan sits relatively alone in the lower left, indicating he was distinctly poor in both.

Data via Baseball Prospectus

In 2016, McGowan was second-to-last in baseball in called strike probability; the only pitcher with a worse mark was his new teammate Brad Ziegler. McGowan wasn’t quite that low with called strikes above average, coming in at 251st out of 273, but no other pitcher had quite the difficulties with both numbers like McGowan did.

It’s worth noting that while he’s been poor by both of these command and control measures in his time as a reliever, by far McGowan’s worst marks came in 2016, coinciding with his re-emergence as a viable bullpen arm.

So how was he able to have his worst command and control to date, yet find such overwhelming success?

It boils down to two key factors: increased use of his two-seam fastball and slider while recapturing the vertical movement of the latter. First, let’s check out his pitch type usage.

Chart via Brooks Baseball

McGowan cut the use of his four-seam fastball by almost 17 percentage points last season, instead opting to throw both his two-seamer and slider with more regularity. He also cut his use of the changeup almost in half. The curveball has never been a big part of his repertoire, and he ditched it almost completely.

When you look at the particulars of each pitch, this new approach makes sense.

His two-seam fastball doesn’t generate a lot of swinging strikes, but with almost five more inches of arm-side run than the four-seamer while maintaining the same velocity, it’s made for getting ground balls. Plus, the two-seamer’s 74.2 percent contact rate outside the zone — 18.2 percentage points more than his next highest pitch — means it generates a ton of weak contact. By increasing its usage so drastically, McGowan is playing to his strengths.

Take that ground ball-inducing soft contact and add the ability to coax swings and misses, and you’ve got McGowan’s slider. It hasn’t always been a pitch that’s generated whiffs and grounders; in fact, for the two years before 2016 it’s been a subpar offering.

The difference is clear as day: In 2016, McGowan was able to recapture the vertical movement that made the pitch so effective in 2013.

Chart via Brooks Baseball

“Recapturing the vertical movement” is a weird way to put it since the pitch now, at its best, has almost no vertical movement. But in the previous two seasons, it had some rise to it, which seemed to work against it. Finding this break on his slider once again meant McGowan was able to keep the pitch down and out of the heart of the plate more consistently. You can visualize this with his pitch percentage zone profiles from 2014 and 2015 (left) compared to 2016 (right).

As you can see, there was a tangible difference in where he was able to locate the slider, and his ability to keep it down had a huge effect on the pitch’s success.

Before last season, it looked like McGowan was finished, but with some changes to his pitch usage combined with recapturing his good slider, he went from unusable to excellent. The margin for error in baseball is so small that it only takes a couple of minor adjustments for everything you thought you knew to be wrong.

One thing’s for sure: I won’t ignore Dustin McGowan any longer.