When former first-round draft pick Hunter Harvey took the mound for his major league debut in Boston on Saturday, he became the 54th player to wear an Orioles uniform in 2019.

Last season, the Orioles set a franchise record by using 56 players, leaving this year’s club three shy of breaking that mark with 38 games to play.

Roster expansion is soon approaching, and this is the last year in which clubs can carry up to 40 players in September. (Starting in 2020, teams can carry only 28 in the season’s final month.) The Orioles could find room for at least three more players to make their 2019 club debuts and surpass last year’s roster total.

Without even considering any possible waiver claims or minor league trade acquisitions, here’s a look at some of the in-house candidates to make their first Oriole appearances of 2019 before the year is out.

DH MARK TRUMBO

The 2019 season has been a lost cause for Trumbo, even moreso than 2018. Last year, despite missing the first and last months of the season with injuries, Trumbo still managed to appear in 90 games. This year, he won’t get half that number, if he plays at all. The 33-year-old, attempting to work his way back from last September’s right knee surgery, has twice been forced to halt his rehab assignments because of continued discomfort in his knee.

Trumbo, who’s in the final season of a three-year, $37.5 million deal he signed in January 2017, recognizes that his major league playing career is winding down. Still, he hopes to take the field in September for the Orioles if he’s physically capable.

1B/OF RYAN MOUNTCASTLE

A case could be made that Mountcastle, the Orioles’ top position prospect not named Adley Rutschman, would be one of the best hitters in the major league lineup if he were called up today. After homering Sunday for Triple-A Norfolk, Mountcastle is batting .312 with a team-leading .864 OPS, 22 home runs and 73 RBIs, although he’s walked just 20 times in 489 plate appearances. And he’s doing this while, at 22, being nearly five years younger than the average Triple-A position player.

The Orioles, though, haven’t given much indication they’ll call up Mountcastle this year. They’re still trying to find a long-term position for him; he’s spent the majority of the season at first base, but 10 of his 14 starts in August have come in left field. He’s also started nine games at third base, his primary position last season. The Orioles could elect to keep Mountcastle at Norfolk the rest of the season and the start of 2020 to work on his defense and plate discipline. By delaying his promotion until then, they’d earn an extra season of team control.

OF AUSTIN HAYS

Back in spring training, it seemed more a matter of when, not if, Hays would play for the Orioles in 2019. Hays tore up the Grapefruit League with a .351 average, 1.277 OPS and a team-leading five home runs and 13 RBIs, making a bid for an Opening Day roster spot on a club with an unsettled outfield. Instead, the Orioles reassigned him to minor league camp, where he sprained his thumb and has been left playing catch-up ever since. Hays made his season debut at Single-Frederick in mid-May, worked his way through Double-A Bowie and onto Norfolk, only to suffer a hamstring injury June 19 that landed him on the injured list again. He rejoined the Tides on July 11.

Hays’ offensive numbers aren’t overwhelming for the club’s No. 4 prospect (per MLB.com) and 2017 Brooks Robinson Minor League Player of the Year. He’s hitting .250 with a .776 OPS, eight homers and 22 RBIs. Still, a call-up to the Orioles seems likely for the 24-year-old, who has plenty of offensive potential and is a better defensive center fielder than Anthony Santander and converted infielder Stevie Wilkerson. Hays’ major league clock already began in 2017, when the Orioles promoted him for a September audition, so his service time issues shouldn’t be a big concern for Mike Elias and the front office. Plus, he’s already on the 40-man roster.

OF MASON WILLIAMS

Williams, signed as a minor league free agent at the end of spring training, has been an integral piece of the Norfolk lineup in 2019. Williams, who turns 28 on Tuesday, ranks behind only Mountcastle in OPS (.859), homers (17) and RBIs (61), and his .313 average is the best of any player who’s been with the Tides all season.

Those, however, are the key words: he’s been with the Tides all season. The fact that Williams hasn’t gotten a call-up to the majors yet, even with the game of musical chairs that’s been happening in the Orioles’ outfield for much of the year, indicates that the Elias regime considers him more minor league depth than big league material. Still, if the Orioles decide they need an extra outfielder in September, and they’re willing to clear a 40-man roster spot, Williams could find a spot on the roster. He put up decent big league numbers in a 51-game sample with the Cincinnati Reds last season, batting .293 with a .729 OPS.

LHP KEEGAN AKIN

The only legitimate Orioles’ starting pitching prospect who began the year at Triple-A, Akin figured to be one of the first men up this year whenever a need arose in the Baltimore rotation. It hasn’t worked out that way, in large part because of Akin’s inconsistency. After a disastrous eight-run, 3 2/3-inning outing Sunday, Akin is 5-6 with a 4.92 ERA in 23 games (22 starts), averaging nearly 4.5 walks per nine innings. He has only four starts this year of six or more innings, and just one since May 16.

That said, Akin, the Orioles’ 2018 Jim Palmer Minor League Co-Pitcher of the Year, is still a phone call away if the Orioles’ rotation depth becomes further depleted down the stretch. He’s not currently on the 40-man roster, but he’ll need to be added to it this winter to protect him from being selected in the Rule 5 draft. So the Orioles might not mind adding the 24-year-old a couple months early to let him get some instruction from the major league staff.

RHP RYAN EADES

If this name doesn’t ring familiar to you, it’s understandable; Eades has been in the Orioles’ organization for less than a week. Eades, a second-round pick by the Minnesota Twins in 2013, climbed up the organizational ladder to make his debut in June at age 27, only for the Twins to designate him for assignment after two appearances. He allowed six baserunners and struck out five in 3 2/3 scoreless innings for Minnesota.

The Orioles claimed Eades on waivers Aug. 14 and optioned him to Norfolk, where he’s pitched once so far, throwing a scoreless inning Aug. 17. With two options remaining, he could soon join the shuttle of relievers who have split their time between Baltimore and Norfolk this year, alongside the likes of Evan Phillips, Branden Kline, David Hess and Tanner Scott.

LHP HUNTER CERVENKA

Another recent Orioles acquisition, the Texas-born Hunter Cervenka is no relation to Orioles minor league catcher Martin Cervenka, a native of the Czech Republic. Hunter Cervenka, 29, burst onto the scene in the Atlanta Braves’ bullpen in 2016 with a 3.18 ERA in 50 games, but his career stalled after he was traded to the Miami Marlins that August. He hasn’t pitched in the majors since 2017. The Orioles are his seventh organization, and this is his second stint; he was an Oriole for 16 days in March 2018 but was cut at the end of spring training.

Re-signed two weeks ago, Cervenka is off to a blazing start at Norfolk. In four appearances, he’s tossed five scoreless, two-hit innings, striking out eight of the 16 batters he’s faced without issuing a walk. Considering Richard Bleier’s struggles and Scott’s inconsistency, the Orioles could use left-handed help in the major league bullpen. Cervenka might be the guy to supply it.