Joe Musgrove Was Simply Electric in His Houston Astros Debut

Musgrove passed a tough test with flying colors in his MLB debut.

It was the gasp heard 'round the world. It was the sound of 24,399 people at Minute Maid Park collectively holding their breath as stud youngster Lance McCullers left the field due to an injury in the fifth inning with the Houston Astros hosting the Toronto Blue Jays.

McCullers had already notched six strikeouts on the night to lower his season-long skill-interactive ERA (SIERA) to 3.64. With the Astros needing to make up ground to reach the postseason, a good chunk of their hopes rode on that man's right arm.

Then, as the game went along without McCullers, a bit of a different noise came from the diamond. Instead of a sigh, it was a whiff. Then another. And another.

It was the sound of Joe Musgrove announcing his presence in his big-league debut.

Musgrove pitched the final 4 1/3 innings, striking out 8 batters while allowing only 1 hit and 1 walk. The Astros didn't win the game, but that certainly wasn't Musgrove's doing. And the further you dig into his outing, the more impressive it becomes.

Swinging Strikes for Days

Whenever we have such a small sample for a guy, it's hard to get overly excited about the performance, no matter how many strikeouts he gets. It's possible the umpire was just feeling a bit generous with the strike zone, inflating any surface-level numbers.

That's why we should turn to things such as swinging-strike rate and contact rate. Instead of a sample of 15 batters (the number Musgrove faced Tuesday), we get every pitch that he threw, painting a clearer picture of his dominance level for the day.

This makes it more obvious that Musgrove just torched the Earth.

Here's how his plate-discipline stats compare with those of the average big-league starter in the American League. Swinging-strike rate is the percentage of pitches that result in a swing and a miss, and contact rate is the percentage of swings on which the opposing batters make contact.

Pitcher Swinging-Strike Rate Contact Rate
Joe Musgrove 16.7% 62.1%
A.L. Average 9.4% 79.6%

That is what you can call the distribution of silly sauce. It's simply not fair.

For some additional context on what Musgrove did, the league leader in swinging-strike rate among qualified starters this year is Clayton Kershaw at 16.1%. The second-best mark belongs to Max Scherzer at 15.1%. He topped both of them against one of the best offenses in baseball.

You could argue that we should ding Musgrove a bit because he was working in relief, meaning he could reach back a bit more than a starter would be able to. That's fair, but he'd even rank seventh among relievers in swinging-strike rate, ahead of both Andrew Miller and Dellin Betances. You'll have to look elsewhere if you're trying to dismiss what he did.

What to Expect Going Forward

Ideally, the Astros would be able to keep Musgrove in the bullpen to continue melting the faces off of opposing batters. That just might not be an option right now.

The team was prepared to use Musgrove on Monday in case Doug Fister had to be on paternity leave, so it would seem logical that he would simply slide into McCullers' spot if he were forced to miss some time. So what could we expect if that were to happen?

Even if Musgrove weren't striking out over half of his opponents, you could still expect him to excel. In now 89 2/3 innings at all levels this year between Double-A, Triple-A, and the majors, Musgrove has a 26.8% strikeout rate with a 14.0% swinging-strike rate. He can get strikeouts, and last night wasn't just some flash in the pan.

What Musgrove is truly known for, though, is his control. The walk he issued last night was just his 11th of the entire season, bringing his walk rate to 3.1%. There aren't many dudes in their age-23 seasons who can do that, and it gives Musgrove a boatload of wiggle room in the event he gets into trouble.

This combo of a high-strikeout, low-walk arm should allow Musgrove to succeed if he has to enter the rotation on a full-time basis. He has never thrown more than 100 2/3 innings in a season, and he's already approaching that this year, so you'd assume the Astros would prefer to avoid that. But from a pure effectiveness point of view, he has the arsenal to get the job done.

Musgrove's debut last night was more than just one dazzling performance: it was a glimpse at his potential for the team. This is a guy who has been dominant the entire season in the minors, and we shouldn't expect that to end now that he's up with the big club.