Padres' New Statcast Data Reveals Just How Dominant Mason Miller Really Is

[Randy Holt]

In Mason Miller, the San Diego Padres have the best relief arm in baseball coming out of their bullpen. 

The wild thing is that the above sentiment isn't opinion. It's as objective an idea as possible considering his blend of velocity, strikeouts, and overall ability to prevent runs. As the calendar hits the middle of June, Miller is one of the only certainties the Padres possess on a roster full of questions. 

Miller's 1.9 fWAR through his first 29 appearances leads all qualifying relievers. As does his remarkable 51.8 percent strikeout rate (Miller has faced 114 hitters as of this writing and struck out 59 of them). His 0.90 ERA ranks fifth among that group, but he's also allowing the least amount of hard contact by a wide margin (14.0 percent) in those rare instances in which a hitter even gets a bat on the ball. Miller's 51.9 percent contact rate is the best in the sport by more than seven percent. His 101.3 MPH fastball velocity also sits at the top of the leaderboard.

For an illustrated indicator of just how good he's been, take his Baseball Savant percentile chart. He ranks in the 100th percentile for (i.e., he's the best in baseball at) the following: xERA, xBA, fastball velocity, average exit velocity allowed, barrel rate allowed, hard-hit rate, whiff rate, and strikeout rate. Oh, and his chase rate and ground-ball rate also rank in the top 10 perecent among all pitchers league-wide.

Given all of that, we didn't necessarily need new reasons to be impressed by Miller. He was already one of the game's top closers upon his arrival in San Diego and has only increased in his dominance in the trips he's taken to the mound since. However, Statcast's new data has given us even more ways in which that dominance can be quantified. 

The introduction of the swing timing and the miss distance leaderboard unlocks additional insight into the impact of pitches. We now have more of a tangible means to describe just how much certain pitchers can overwhelm the average hitter. The miss distance helps to indicate just that; it's the closest distance (in inches) between the top half of the bat and the ball over the course of a swing. Swing timing, meanwhile, helps to indicate how in front of or behind, above or below, and horizontally centered a swing ends up on a given pitch or pitch type.

In Miller's case, that data is illustrated below in a couple of different ways. The red curve is his fastball; the yellow curve is his slider.

Let's talk about the fastball first. Hitters are able to keep it centered, sure. A four-seam isn't liable to feature too much horizontal movement to it, after all. What's more notable is in the timing and the vertical components. Hitters are much more liable to be behind. They're not getting completely overpowered given the overall velocity present in the game, but they're much more likely to be behind than directly on time, and they're certainly not going to be early. When you factor in the vertical movement in which a four-seamer moves upward — Miller gets 16.9 inches of induced break — it becomes nearly impossible for a hitter to make quality contact. In Miller's case, the 22.7 percent hard-hit rate he's allowing is more than 25 percent lower than it was last year. 

The slider is, perhaps, an even more impressive picture. In each of the three areas of the swing, hitters are all over the map. They're off the end of the bat, they're swinging early, and they're swinging over it. A "flawed" swing in the eyes of this new data is a swing in which a hitter fails on all three fronts. Miller's 37 percent rate of flawed swings with his slider isn't just the highest rate among any individual pitch type for any Padres pitcher, but the highest of any individual pitch for any pitcher in the sport. The 60 percent whiff rate with the slider is also atop the leaderboard, while his 67 percent rate of competitive swings is the lowest for any pitch.

It's not just that Mason Miller is likely the most dominant reliever in the sport. He also possesses its most dominant pitch in his slider. That four-seam/slider combination is not a modern invention in baseball, but Miller is executing it as well as anybody we've seen in recent memory. The idea itself is not revelatory; Miller was already having an elite season by just about any measure. Statcast's new data is just another perspective to reinforce it.

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