Heading into the 2021 season, just about anyone connected to the Orioles or Orioles fandom would have been happy with some advance knowledge that Ryan Mountcastle would finish the season with 33 home runs, leading both the team and American League rookies. You could hardly hope for better than that from a 24-year-old prospect who snuck into the back end of top 100 lists as he entered his first 162-game season.
Whatever else can be said about Mountcastle, this much should remain true: If he is capable going forward of hitting at least as well as, or better than, the way that he hit in 2021, there should be a place for him as the Orioles rebuild phase transitions into what we all hope will be an Orioles success phase.
In the two big park/league-adjusted stats, OPS+ and wRC+, Mountcastle’s .255/.309/.487 batting line put him at 112 and 111, respectively. That is, he was 11 or 12% better than the league average batter. Any playoff-contending team can find a place to put that kind of player somewhere in their lineup.
Having said that, there are two basic problems for Mountcastle. The first is that hitting 30+ home runs is not as special as it used to be. Ten years ago, there were only 24 players in MLB who hit at least that many homers, with only nine exceeding Mountcastle’s 2021 number of 33. These were, largely, the game’s premiere sluggers. In 2021, there were 42 such players.
The other problem for Mountcastle is that his professional career has been one of sliding down the defensive spectrum. When he was drafted by the Orioles in 2015 with a pick the O’s received for Nelson Cruz signing elsewhere, Mountcastle was a shortstop. As he climbed the ladder in the minors he moved to third base, and when he debuted in MLB in 2020, he’d slipped from the hot corner into left field. This year, the Orioles saw enough of Mountcastle in left field to move him to first base.
It’s tougher to find players capable of competently playing shortstop than it is to find players who can acceptably play third base. This is true also for third base compared to left field, and left field compared to first base. Across all of MLB this year, shortstops combined for a .736 OPS. If we were comparing Mountcastle to shortstops, where he would have trailed only Fernando Tatis Jr. in home runs, he would look better. First basemen, on the other hand, had a .792 OPS.
Between the proliferation of home runs and the limitation as a first baseman/designated hitter, Mountcastle is more of a “just another guy” kind of player rather than a difference-maker. That is reflected in how he is measured by Wins Above Replacement. At Fangraphs, Mountcastle finished with 1.4 WAR. On Baseball Reference, he doesn’t even crack 1, sitting at 0.9.
One of former manager Buck Showalter’s folksy bromides was, “Don’t overlook an orchid when you’re searching for a rose.” The roses are the top-tier prospects like Adley Rutschman and Grayson Rodriguez. If the Orioles are going to ascend from the depths and compete for playoff spots, they’re going to need stars to get them a lot of the way there. They’ll also need to plug in players like Mountcastle because you can’t get a star everywhere.
Performing the way that he did in the first full 162 game season of his career was a sign that Mountcastle did some growing as a player. One of the big knocks on him was that he did not walk enough, with just a 4.6% walk rate as a minor leaguer.
In 2021, Mountcastle improved to a 7.0% walk rate. While that’s still only in the 25th percentile among MLBers, it’s a huge step up for Mountcastle. Had he only walked at his minor league rate, he’d have been below the dreaded .300 OBP mark and would seem more like a placeholder player who will be shuffled out once the Orioles are actually trying to be good.
Another area where Mountcastle saw improvement compared to his minor league performance was in his power. That’s measured by isolated slugging, or ISO, which is calculated by taking a player’s slugging percentage and subtracting his batting average. As a 21-year-old at Double-A in 2018, Mountcastle’s ISO was .168. At Triple-A in 2019, he was up to .215. His partial 2020 season performance had an ISO of only .159, but in 2021, he posted his best ever, at .232.
Across all of MLB in the 2021 season, there were 188 players with at least 400 plate appearances. Mountcastle’s ISO places him 36th out of 188. That’s respectable, if not legendary. (His 7.0% walk rate was 139th.) He has grown into power that Dan Duquette and company surely hoped he would when drafting Mountcastle six years ago.
Can Mountcastle improve even further still? Or, if not that, can he hold 2021’s gains for several years going forward? It’s not hard to see what his problem was from looking at his Statcast pitch values. Mountcastle struggled the most against changeups, batting just .171 when putting them in play, slugging only .257. He had his largest whiff percentage (41.5) against changeups and his worst hard-hit percentage (19.1).
It is safe to say that other MLB teams will have noticed Mountcastle’s problem. If he does not adjust, he could be in for a sophomore slump. If Mountcastle does adjust with either offseason, spring training, or in-season work, then the league will have some problems dealing with him now and in the future.
Mountcastle also had a very poor first month of the season. At the end of April, Mountcastle had just a .515 OPS and had only hit one of his eventual 33 home runs. Was this the result of him being challenged in a way that he hadn’t before, and he eventually adjusted to that challenge? Fans can hope so, as the player Mountcastle was over the season’s remaining months is much more interesting. He batted .266/.324/.528 from May 1 on.
You can’t just hand-wave away slumps. They happen. But maybe next year’s slumps won’t be as bad or last as long, now that Mountcastle is a more experienced player.
This is the first offseason where Mountcastle is going to head into it with a real, defined future role. The fact that Chris Davis is finally out of the picture means there’s not much of a logjam at the 1B/DH spot. He can mix with Trey Mancini, assuming Mancini isn’t traded. He should not need to play left field any more. Perhaps this will help him as he is able to settle in.
Mountcastle only turns 25 years old next February. Assuming there are no changes to service time years in baseball’s next CBA, Mountcastle is not set to be eligible for salary arbitration until 2024 and will not become a free agent until after 2026.