A year ago, Wade Miley went to camp with the Brewers as a 31-year-old minor-league free agent. He was coming off a disastrous season that saw him finish with a 128 ERA- with the Orioles. In truth, Miley wasn’t quite that bad — he also finished with an xFIP- of 106. But even 106 is unspectacular, and going into the season, expectations were modest. It wasn’t even guaranteed Miley would ever find a spot.

He wound up making 16 starts in a Brewers uniform, plus four more (technically) in the playoffs. In one sense, the Brewers got what they might’ve expected. Once again, Miley finished with an xFIP- of 106. But then, his ERA- settled at a ridiculous 63. In other words, while his xFIP- stayed exactly the same, he cut his ERA- in half. Miley finished with a better park-adjusted ERA than Corey Kluber. He finished with a better park-adjusted ERA than Gerrit Cole. He finished with a better park-adjusted ERA than Clayton Kershaw. The best and worst thing about baseball is that it doesn’t always have to make sense. Through one lens, Miley pitched as the ace of his team.

And now he’s going to take his pitching to Houston. Miley has signed with the Astros for a year and $4.5 million, with another $0.5 million in incentives. The Astros are likely to lose Dallas Keuchel. In Miley, they’re hoping to find an approximation.

Like Keuchel, Miley is a ground-balling southpaw with an underwhelming fastball. He’s never really suffered a major arm injury, and he pitches more around the zone than inside of it. Miley isn’t a high-strikeout sort, and he throws almost everything down, looking to get weak contact off the bat. Miley just finished fourth among starters in expected wOBA on batted balls. Keuchel finished eighth. The parallels are numerous, even though Keuchel has the far more impressive track record.

As Miley pitched in 2018, he didn’t just end up with a lower ERA. The major change he made was that he leaned heavily — and primarily — on a new cutter:

It’s a cutter he commanded well to the glove-side:

The cutter just rescued Anibal Sanchez’s career. The year-to-year increase in Miley’s cutter rate is one of the very largest on record. If you look only at 2018, you might think the cutter has turned into a magical pitch. Check out how the cutter-heavy starters out-pitched their peripherals:

On the other hand, 2017 wasn’t that long ago, and:

So we don’t have anything conclusive. Just some anecdotal hints. Last season, armed with a new cutter, Miley was able to suppress quality contact. He also finished with the 14th-worst K-BB% among 179 starters with at least 50 innings. Miley was simultaneously easy to hit and hard to hit. It worked out well for him for as long as he pitched.

We might not need to overcomplicate things. Going back to 2002, there have been more than 2,000 starters with at least 50 innings in consecutive seasons. I wanted to focus on the guys with the biggest differences between ERA- and xFIP-, like what Miley just put up. In year one, the 50 guys with the biggest differences averaged an ERA- lower than their xFIP- by 41 points. In year two, the difference regressed to two points. In year one, the 25 guys with the biggest differences averaged an ERA- lower than their xFIP- by 48 points. In year two, the difference regressed to…zero points. Just nothing to be found. Historically, xFIP has won out. Historically, regression has happened. Just because it feels like old sabermetrics doesn’t mean the principles don’t still apply.

So even though Miley just maintained a low ERA, even though he just generated weak contact, the number to keep in mind is that xFIP- of 106. Perhaps the Astros will squeeze out a little bit more. I don’t know if they’ve put together a detailed pitching plan. If they have, I don’t know if it’ll be an effective one. The best-case scenario is that Miley really does pitch like another Keuchel. Perhaps he’ll pitch like another CC Sabathia. There’s also a great chance he pitches like Wade Miley. That is, like a fourth or fifth starter, who needs a good defense behind him.

Thankfully for the Astros, they’re already great. Miley isn’t someone they need, not all season long. He’ll eat some innings until Forrest Whitley can pitch. He’ll eat some innings when Joshua James needs a break. He’ll eat some innings when Collin McHugh needs a break. And so on and so forth. Maybe the Astros feel like they have the key to making Miley terrific. More likely, they’re just fond of a good cutter, thrown by a durable arm. Miley and Keuchel do enough of the same things that you can’t blame the ballclub for choosing this path.