What's behind Bobby Miller's historic start?

This story was excerpted from Juan Toribio’s Dodgers Beat newsletter. Paul Casella is pinch-hitting for Toribio in today's newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

At a time when the Dodgers’ rotation needs all the help it can get, Bobby Miller has not only provided a boost -- he’s made history in the process.

Through four starts, the 24-year-old righty is 3-0 with a 0.78 ERA. He’s struck out 23 batters and allowed only 12 hits. No other pitcher in AL/NL history has matched each of those totals in his first four games.

It’s been a remarkable run by the Dodgers’ top pitching prospect, but being only four games, there are still plenty of questions: How’s he done it? Is it sustainable? Has he secured a rotation spot? When can you see him next?

Let’s take a closer look.

Miller didn’t exactly dominate in the Minors … so how’s he doing this?

Miller had a 5.65 ERA in four starts with Triple-A Oklahoma City before being called up this season. Overall, he has a 4.43 ERA in 31 career appearances at the top two levels of the Minors.

So, what changed in the Majors?

“I couldn’t really tell you,” Miller said. “I guess maybe just the game-planning is a little bit better, adrenaline is a little bit higher, more people in the stands, locked in a little bit more.”

Manager Dave Roberts also gave some credit to game planning, as well as working with catcher Will Smith and Miller’s pitch mix. While the righty already had a big league fastball -- he’s thrown 17 pitches of at least 100 mph and he’s maxed out at 100.4 mph since joining the Dodgers -- it’s been the way he’s worked in his slider, changeup and curveball that has helped him reach another level.

Miller has a 42.6% whiff rate with his slider and a 35.0% whiff rate with his changeup. Though his curveball has been his least-used pitch (9.9% usage rate), it's produced a 43.8% whiff rate.

It’s obviously a small sample, but Miller is one of only five starters with multiple pitches registering a whiff rate of at least 42%. The other four: Spencer Strider, Yu Darvish, Blake Snell and Kodai Senga.

“He’s performed better than he did in the Minor Leagues, so it kind of doesn’t make a whole lot of sense,” Roberts said. “But I do think there’s something to the honed focus, the pitch mixing and knowing that these games really matter -- it’s not about development anymore. And I think he’s embraced that.”

Is this sustainable?

Opposing hitters will undoubtedly make adjustments once the scouting report is out on Miller. Still, the metrics suggest that very little about Miller’s historic start has been the result of luck.

Along with ranking among the best pitchers in many traditional stats since his arrival, Miller also ranks among the top 5% of pitchers in key expected metrics such as xERA, xwOBA and xSLG.

Miller has done all of this while facing the Braves and Yankees -- two of the five highest-scoring teams over the past month -- as well as a Phillies lineup that features Bryce Harper, Trea Turner, Kyle Schwarber and Nick Castellanos.

“The starts that he’s made have been against some really good lineups,” Roberts said. “So that’s something that should show him that if he can go out there and make pitches and keep his poise, he can navigate any lineup.”

Has he earned a permanent spot in the rotation?

Julio Urías (strained left hamstring) will eventually rejoin the rotation. The Dodgers hope to get Dustin May (right forearm strain) back at some point in the second half, while Noah Syndergaard (7.16 ERA) is also on the IL with a blister issue.

But if Miller continues to pitch even remotely as well as he has to this point, he won’t be leaving the rotation -- regardless of who’s healthy.

“When you play for this club, we’re not about development -- we’ve got to win,” Roberts said. “It doesn’t matter the age, the service time -- if you’re going out there and performing, then you earn those opportunities.”

When will he pitch next?

Though the Dodgers haven’t announced probables beyond this series with the White Sox, Miller’s spot in the rotation is next due up Friday against the rival Giants at Dodger Stadium.