Ryan Mountcastle has been the guy since his call-up in August

On August 21, 2020, it finally happened for Ryan Mountcastle. After being drafted in the first round of the 2015 MLB draft, the 23-year-old had spent five seasons hitting his way through the Orioles minor league system before getting the call-up to the Big Show.

It hadn’t been a clear path to the majors for Mountcastle. A natural shortstop, his glove was deemed enough of a liability that the Orioles moved him to third base. And then, after more lackluster fielding, to first.

Unfortunately, first base is exactly where the Orioles have long had something of a traffic jam. There always seems to be a glut of power-hitting free swingers to rotate between first base and DH: Christian Walker, Mark Trumbo, Trey Mancini, and Renato Núñez are just a partial list. Worse, of course, is the seven-year, $161,000,000 logjam created by a first baseman allowed to play even after he stopped hitting in 2016. From 2015 to 2019, Chris Davis never made fewer than 97 starts a season at first base. And even after the 2020 season, when, to most fans’ delight, manager Brandon Hyde finally made the call to bench Davis, his heir apparent remains Trey Mancini, who everyone hopes will make a full, healthy return from cancer next season.

Which is why, since July 2019, Ryan Mountcastle has been working out with an outfielder’s glove. People have been unimpressed, so far, with the results. As our Tyler Young summarized, just over a month ago:

MLB Pipeline’s scouting report on the Florida native explains that he possesses “a below-average arm and limited range.” FanGraphs adds to that by saying “beware the swing-happy hitter with no position[.]”

The other big issue with Mountcastle has been his batting eye. Ever since fans started knocking on Mike Elias’ door, begging for Mountcastle to be let up to the bigs, the Orioles GM has stated in no uncertain terms that he wouldn’t rush the prospect’s development—and that Mountcastle was going to have to do better than the measly 4.3% walk rate he had with Norfolk in 2019 in order to be trusted with the job.

In some ways, Covid-19 changed that calculus. As Elias explained in an August 22^nd interview:

With the lack of a minor league season this year, it made for a very strange calculus where we wanted him to get work in in left field, we wanted him to work on the offensive development goals that we had for him. But there were no real games to be played. At some point, it’s in his best interest to go see some other uniforms and play some real games.

We feel he’s in a decent enough spot in terms of his comfort level in left field to at least survive out there right now. He might surprise us out there, he’s a good athlete. He performed well in Bowie, he walked more than he struck out and there were some really legit arms down there throwing at him.

As it’s turned out, the pandemic wiping out the 2020 minor league season forced Elias & Co.’s hand, leading them to throw caution to the winds and promote Mountcastle—even when, as Elias’s careful language shows, they weren’t fully convinced he’d be ready for the job.

Maybe the fans knew better. So far, Ryan Mountcastle has performed above expectations in all senses.

In the field, Mountcastle has amply passed the eye test. Last night, Orioles beat reporter Joe Trezza tweeted:

The numbers bear this out. This chart, created by BaseballSavant, ranks all fly balls from 1-5 by degree of catch difficulty. This season, Mountcastle has missed no balls in Categories 1 or 2, just one in Category 3, one in Category 4, and one in Category 5. Oh, and check out that lone red dot in the second-to-bottom-left corner: that’s a tough catch!

Overall, as a left fielder Mountcastle has a successful fielding rate of 94% and exactly 0 outs above average (those could be better, of course, but they sure beat Dwight Smith Jr.’s 76% success rate and -3 OAA in 2020). Far from a liability in left field, it turns out that Mountcastle’s defense has been utterly, completely, delightfully average.

Hitting-wise, the results speak for themselves. In just over a month of play, Mountcastle is hitting .325 with 5 HRs, 22 RBIs, and an .878 OPS. (An oft-asked question from fans: when do offensive sample sizes become reliable? FanGraphs has found that, for several hitting categories, small sizes correlate to the real deal at around 100-150 plate appearances. So Mountcastle’s 127 PA is not ideal, but not so few that we’re using a divining rod, either.)

Let’s start with the bad news: Mountcastle’s BABIP is a quite-high .388, his average exit velocity (87.6) is below the MLB average of 88.3 mph, and his K rate of 23.0% is elevated (although if he got back to his career minor league rate of 20.1%, he’d be fine).

Now onto the good: Mountcastle’s other peripherals are all pretty much above average. This includes barrel percentage (7.2), hard hit percentage (42), sweet spot percentage (37.3), expected batting average (.277), expected slugging (.466), and weighted on-base average (.377). He can hit offspeed stuff: he’s batting .372 on breaking balls and slugging .750 on changeups. He can hit situationally: he’s hitting .333 with runners in scoring position, and .406 with two outs. He can use the field, as the spray chart below shows.

And, if you were wondering, his walk rate of 8.2% is up from his career rate of 4.6% in the minors, and a perfectly average figure for the MLB, if he can keep it up.

For a long time, the Orioles front office was determined to keep Ryan Mountcastle ripening on the vine until he was good and ready to stick in the big leagues once he arrived. One month in it seems fair to say, so far, so good.