How Mason Miller is (somehow) getting even better

This story was excerpted from AJ Cassavell’s Padres Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

SAN DIEGO -- Mason Miller was already one of baseball’s best relief pitchers when San Diego traded for him last summer.

But the Padres weren’t trading for what Mason Miller was. (Even if Miller already was a lights-out weapon with the game’s premier four-seam fastball and a wipeout slider to go along with it.) When they traded for him, the Padres knew they had 4 1/2 years of control with Miller.

And they envisioned him getting better.

So far, it looks like they were right. Miller has become a better pitcher since he was traded from the A’s to the Padres last summer. Ahead of his first series against his former club this weekend, here’s a look at the biggest ways in which Miller has improved since joining the Padres:

Sliders for strikes

This was always the most important next step for Miller to take. His Baseball Savant page is littered with dark red, indicating that Miller is among the best of the best in nearly every category. And then, there’s that 12% walk rate from last season -- checking in in just the sixth percentile.

Generally speaking, Miller’s fastball command is solid enough. He doesn’t paint it. But with that kind of velocity, he doesn’t need to paint. When he absolutely has to, he can throw his fastball for a strike.

But put yourself in the mind of an opposing hitter. Say you’ve got the count in your favor, and you know Miller needs to throw a strike. Now, say he’s only capable of doing that with one pitch. Why not cheat hard to the fastball? These are big league hitters. Even Mason Miller’s fastball is hittable when they know it’s coming.

“The consistency and the confidence in my slider has been [critical],” Miller said. “I’ve been able to throw it more for strikes, in different counts.”

It’s a tricky thing to analyze, because we don’t know exactly when Miller is trying to throw his slider in the zone and when he’s trying to throw it out of the zone for chase. But when he throws a slider in a three-ball count, that’s a pretty good indicator that he’s trying to throw it for a strike.

Heading into this week’s series against the Dodgers, Miller had landed seven consecutive three-ball sliders in the strike zone with the Padres. (He doesn’t get to three balls often, so he’d only thrown eight in his entire Padres tenure.)

In his season and a half working as a reliever with the A’s, Miller threw a grand total of 15 three-ball sliders, and he landed only seven of them. Long story short: You can’t cheat to Mason Miller’s fastball anymore. He’ll probably make you look silly with his slider.

Of course, as if to illustrate its importance, Miller threw three-ball sliders to Freddie Freeman and Max Muncy this week, and missed with both of them. That led to two of Miller’s more laborious outings -- including his first loss as a Padre on Tuesday night.

Nonetheless, as a direct result of his improved slider command, Miller is throwing the pitch at a higher rate than ever, around 50%. That’s right where Miller wants it -- “close to 50-50, so it’s really like a coin flip.”

Of course, all of this leads to the inevitable question … What did Miller actually change in order to be able to throw his slider for strikes more consistently?

His mechanics are cleaner -- or, at least, more consistently clean

Here’s the thing about Miller’s arsenal: His stuff hasn’t really changed. His velocity and pitch shapes -- on paper at least -- look basically the same. He’s getting better results with them. But they’re the same pitches.

But there’s one area that jumps out as distinctly different from the past couple seasons: Miller’s arm angle. It was consistently in the mid-30s for the first three years of his career. This year, Miller’s average arm angle is an even 40 degrees.

That is not an adjustment the Padres and Miller have made. At least, it’s not a new arm angle for Miller. It’s just that he wasn’t as consistently able to hit that ideal arm angle in the past.

“Over fatigue, or just bad habits, it’s crept down,” Miller said.

This year?

“It’s part of just growing up as a player, too,” Miller said. “Understanding and going through that change. You realize that’s a natural thing. Your arm gets tired, your slot drops.

“So staying on top of drills and stuff like that in the meantime -- that facilitates good habits. That’s all it is is just good habits. It’s really hard to be on the mound and think: ‘Keep your arm angle higher.’ It’s more a byproduct of everything else. And the arm ends up in the right place.”

As a result, the fastball has life, the slider has bite, and Miller is able to better command each.

He’s growing as a pitcher

As with most things in life, the surest way to get better at something is by doing that thing. Mason Miller is getting better at pitching, because he’s pitched more -- and is thus better at making in-game adjustments to ensure that his outings don’t spiral.

“A couple games, for a reliever, is the difference between a really good year and an OK year,” Miller said. “You take away probably two games from my year last year, it’s a really great year. I finished really strong. But I think I’m showing more consistency. … I’m kind of the same guy. Just being a little bit more consistent.”

Monday was one of those outings. Miller’s mechanics were entirely out of whack. To hear pitching coach Ruben Niebla tell it, Miller’s “super strength is his ability to brace into his lead leg.” Which basically means, it’s Miller’s lead leg that drives the rest of his kinetic chain and begins the process that ultimately results in a triple-digit fastball and a wipeout slider.

For a while on Monday night, that lead leg wasn't doing its job. Niebla emerged from the dugout to talk through that fix with Miller. But the reality was, Miller knew it and was already making that adjustment.

Sure enough, nine of Miller’s first 10 pitches that night were balls. Then, after making that adjustment, he threw his final 12 pitches for strikes.

“That’s a pretty big flip of the switch,” said Padres manager Craig Stammen. “It just talks about how mentally tough he is.”

There’s nowhere to hide as a closer. There’s no cover. If your mechanics are out of whack, you have two options: Figure it the heck out. Or you'll probably lose the game.

The Padres believe Miller has become one of the best in baseball at figuring it the heck out. And, ultimately, that’s the difference between being a great closer -- which Miller was when the Padres traded for him -- and an historically dominant closer.

Which Miller is now.