TORONTO — The roster reshuffling has begun for GM Ross Atkins and the Toronto Blue Jays.

Needing to add pitching and subtract from a muddled middle infield depth chart, that process began Saturday when the Jays shipped 28-year-old Aledmys Diaz to the Houston Astros in exchange for 25-year-old right-hander Trent Thornton, an arm Atkins hopes can figure into the major-league rotation plans this season.

Thornton was available because the Astros had a decision on their hands: Either add him to the 40-man roster this week or risk losing an arm with value in the Rule 5 Draft next month.

“Trent is someone that we've targeted for some time and are confident that his deep repertoire and strike-throwing ability allows him to be a factor for our Major League rotation in the near term,” Atkins said.

Atkins and the Jays now have decisions of their own on that front by Tuesday’s deadline to protect players, and there are a number of interesting internal candidates that need to be added to a 40-man roster that currently sits at 36 players if you include Thornton, who pitched to a 4.42 ERA in 124.1 innings with Triple-A Fresno this season and was ranked as the No. 24 prospect in the Houston system by MLB Pipeline.

Additional room could be found by parting ways with extra bodies like Yangervis Solarte, who is staring in the face of a non-tender designation, Dalton Pompey, or middling bullpen arms like Mark Leiter Jr. and Danny Barnes.

Speaking recently at the GM Meetings in California, Atkins noted that he wouldn’t be surprised if they lost a player in the Rule 5 process on Dec. 13, the final day of the Winter Meetings in Las Vegas.

Here are key names to watch that need to be protected:

RHP Hector Perez

Acquired from the Astros in the Roberto Osuna deal at the trade deadline, Perez is a no-brainer to be added to the 40-man roster. The 22-year-old righty’s stuff is electric, and he’s expected to be one step away from the big leagues this summer with Triple-A Buffalo.

RHP Jordan Romano

The 25-year-old from Markham, Ont., was available in last year’s Rule 5 Draft, but went unselected after posting a 3.39 ERA with High-A Dunedin. Romano parlayed that strong season into more moderate success at Double-A in 2018, running up a 4.13 ERA over 25 starts. Thanks to his mid-90s fastball, teams looking for a diamond in the rough could see him as a bullpen option, a la the Joe Biagini success story from 2016.

RHP Patrick Murphy

Injuries have held this big right-hander back, but 2018 amounted to a breakout season with High-A Dunedin, mostly because he was able to put together 152.2 healthy innings while pitching to a 2.64 ERA and an extreme 59.4 per cent groundball rate. The 23-year-old is ready for a full go at Double-A in 2018.

RHP Yennsy Diaz

Another power arm with no experience above High-A Dunedin, Diaz ran up a 3.05 ERA in 147.1 innings split between Low-A Lansing and the Florida State League, limiting opponents to just 113 hits. Having just turned 22 this month, Diaz is still a ways away, but the arm has juice and he could be viewed as a bullpen option.

LHP Travis Bergen

While the goal for most teams is to protect the players with the highest upside, Bergen’s 0.95 ERA and 74 strikeouts in 56.2 bullpen innings this season at High-A and Double-A jump off the page. He’s strictly a reliever, but the seventh-round pick from the 2015 draft is one of the few lefties in the system.

RHP Corey Copping

After coming over from the Los Angeles Dodgers in the John Axford trade at the deadline, Copping impressed Blue Jays officials by striking out 20 and allowing just seven hits in 14 innings at Double-A New Hampshire. Sure, the soon-to-be 25-year-old right-hander walked nine and needs to firm up the command, but he’s on the MLB doorstep.

OF Forrest Wall

Another player acquired at the 2018 trade deadline — Wall came over from the Colorado Rockies in the package for reliever Seunghwan Oh — Wall slashed .263/.343/.402 with 10 home runs and 38 stolen bases, spending the majority of his age-22 season in Double-A. With so many arms and so few spots, it’s very likely Wall is left unprotected.

RHP Jackson McClelland

A 6-foot-5 righty with a fastball that touches triple digits, McClelland is an improvement in command away from being an interesting back-of-the-bullpen piece. With only 6.1 innings above A-ball, McClelland is down the list of potential 40-man additions, despite the big-time strikeout totals (57 in 43.2 innings).

RHP Jon Harris

A first-round pick out of Missouri State University in 2015, Harris has had more downs than ups in his minor-league tenure. The 25-year-old right-hander did post a 13-6 record in 27 starts at Double-A and Triple-A this past summer, but he allowed 166 hits in 148.1 innings, striking out just 108. Teams might see something as a bullpen conversion candidate, allowing the stuff to play up in shorter stints.

RHP Jacob Waguespack

If you’re noticing a theme with a number of the Jays’ deadline deals, you’re not wrong. When you’re trading the likes of Axford, Oh, or, in this case, Aaron Loup to the Philadelphia Phillies, you’re getting back pieces that aren’t exactly highly-valued commodities. Waguespack is a depth option that will battle for a spot in the Buffalo Bisons rotation during spring training and doesn’t need to be protected.

C Max Pentecost

Passed over in last year’s Rule 5 Draft, the 11th-overall pick in the 2014 draft went out and enjoyed a healthy season in Double-A, producing muted numbers with a .253/.283/.401 slash line and 10 homers in 89 games. Catchers that have potential with the bat are hard to find and there’s a .314/.327/.513 finish over his last 39 games to point to, but even heading into his age-26 season it’s hard to envision Pentecost being ready to stick on a major league roster.