The How and The Why of Michael Fiers by Eno Sarris February 5, 2015 We can say some things about how Mike Fiers went astray in 2013, and how changes to his pitching mix, pitches, and spot on the rubber contributed to his return to relevance in 2014. Those things show up just by looking at the different stats and heat maps we have at our disposal. The harder thing to figure out (if it’s at all possible) is *why* these changes worked. First, the how. The release point data is clear. While his vertical release point went unchanged, Fiers’ horizontal release point shifted more than a foot from 2012 to 2013. Go to the video — thanks to Ryan Romano at the Beyond the Boxscore — and you can see that Fiers did change his spot on the rubber fairly drastically in early 2013. (Note the position of his foot with respect to the “C” on the mound, with 2013 on the left and 2014 on the right.) What’s weird is that Fiers had made this change before and it had worked. Thanks to Jesse Sakstrup on The Hardball Times we can see that the pitcher moved from the first base side to the middle from 2011 to 2012. Moving towards the third base side during his better work in 2014 mirrored that first change, and you can see it on his chart at Brooks Baseball. Who knows why he changed his spot on the rubber after a good 2012 season, but he did. The second how is about his cutter. In 2012 and 2014, Fiers used the cutter more than his change. In that terrible year, Fiers used the change more. The cutter was also slower and had more vertical drop in 2013 than it did in the other years. So we have a few hows — a spot on the rubber, and the use, shape, and velocity of his cutter — but we have to put them together to find out the why. Why was Fiers so bad in 2013, when he gave up eight home runs in 22.1 innings? The change on the rubber seems to have an easy why attached to it. By moving closer to right-handed batters, he moved his heat map. Thanks to Baseball Savant, we can take a look at his fastballs against right-handers in 2013 (left) compared to a similar amount of fastballs in 2014 (right). Do you see how his hot zone moved from down the middle to the outside corner? For the numbers oriented, he went from one fastball on the middle third for every 1.6 fastballs on the outside third in 2013 to a one-to-one ratio in 2014. In raw numbers, he nearly doubled the amount of fastballs on the outside corner to righties after the move on the rubber. It’s fairly obvious that more fastballs away from the heart of the zone was a good development for Fiers given how batters feast on those pitches. Why would a few small changes to his cutter make such a difference when the pitch has the worst swinging strike rate and second-worst ground ball rate among his many pitches? The answer may have something to do with diversity. Look at the velocities of his many pitches, year by year. Now look at the vertical movements of his fastball, change, and cutter, year by year. It certainly looks like, between these two charts, you can say that the cutter changed. And that the cutter became more different from his change in 2014. In other words, it no longer had similar velocity and vertical drop as his changeup. In both 2012 and 2014, his cutter and change had bigger gaps between their average speeds and drops. His cutter and fastball also had bigger gaps in velocity since, post-injury, he added a little velocity to his fastball. Everything spread out. While everything got worse for Fiers in 2013, he was proportionally worse against righties than lefties if you compare his rates to what he’d done before. His strikeout rate against lefties in 2013 dropped to 65% of his previous work, but his strikeout rate against righties dropped to 49% of what he’d done before. He gave up 2.7 times more homers per fly ball against lefties, but he gave up 3.7 times as many homers per fly ball against righties. He was relatively worse against righties. And so maybe we have a why to the cutter change as well. Given the fact that big curves and changeups have reverse platoon splits, the cutter is important for Fiers against righties. When the cutter began to look like too much like his change, maybe the package started looking more delightful to righties — who were also seeing more pitches down the middle. It’s important for a right-hander to figure out how to tame lefty batters, of course. But it looks like Fiers has the secondary pitches to handle lefties. In order to get righties out better, he had to move closer to them on the mound and improve his best offering against them. Given that he nearly doubles his cutter usage against righties, and now (once again) throws it more than his changeup, it looks like Fiers figured this out pretty quickly. Why is always a harder question than how. In the case of Mike Fiers, though, we may have been able to answer both the how and the why of his terrible 2013, sandwiched between two good years. And we didn’t even have to mention the the beautiful rise on his 88 mph fastball, which would have put him on the league leader list had he thrown it more.