Appreciating Andrew Miller's slider

The start to Andrew Miller's career didn't exactly go as planned. Five years after he got drafted, Miller was on his third team and was known mostly as one of the prospects in the deal that sent Miguel Cabrera to the Tigers, a deal that is widely considered to be one of the most lopsided of the 21^st century. He relied mostly on his fastball, which could reach the high 90's, and a sweeping curveball that had a nasty bite as a result of his low arm slot and his across-the-body delivery.

In 2012, the Red Sox put an end to Andrew Miller the starter, opting to let him try his hand at a relief role. His fastball velocity jumped a few ticks, but more importantly, he tightened his curve up and added about five miles per hour on what would become his new slider. After relocating to the bullpen, he rode the slider to strikeout rates well above 30%, a World Series, and a 4-year, $36 million contract with the Yankees. Here is an example of his disgusting breaking ball in action:

While his former college teammate Adam Warren has used his exceptional command to break into the big leagues, Miller was never going to be a corner-painting pitcher. The beauty of his simplified fastball-slider combo is that he is still extremely tough to hit, even if he misses his spot by a mile. Take a look at the zone profile for his slider, courtesy of Brooks Baseball:

On sliders that end up in the middle of the strike zone, hitters have a one-in-five chance of swinging and missing. According to FanGraphs' MLB Average heatmaps, hitters swing at 74% of pitches down the middle and make contact 90% of the time, so they whiff about seven percent of the time.

As hard as it is to hit an Andrew Miller slider down the heart of the plate, those "meatballs" might be decreasing in frequency. According to heatmaps from Baseball Savant, it appears his command of the slider is getting better and better:

In even more exciting news, he is getting to the point where he can freeze hitters with what would be a front door slider to righties and a backdoor slider to lefties. Notice the extra green spot in his 2015 heatmap:

If Miller can continue to improve his command, he will be even more fun to watch for years to come. In the mean time, we can all appreciate how he has leveraged his quirky delivery to go from a failed prospect to an elite reliever. His career has been full of ups and downs, but most Yankee fans will certainly agree that his trials and tribulations have been well worth it.