Possible 40-man roster candidates for the Diamondbacks

A list of players who could be taken in the Rule 5 Draft in December if left off the Diamondbacks 40-man roster.

The Diamondbacks have until 6:00 P.M. ET to add players to their 40-man roster to protect them from the major league phase of the Rule 5 Draft. There is also a minor league phase, which goes four rounds, in which players who aren’t on their organization’s respective Triple-A rosters are eligible to be selected. The Rule 5 Draft will take place during the Winter Meetings on December 11th.

I’ll focus primarily on the major league phase of the Rule 5 Draft, since all the candidates will likely be on the Triple-A roster.

Likely to be selected if left unprotected

OF Kristian Robinson

Robinson will be the highest profile name of potential 40-man roster candidates. Once a former top prospect entering the 2020 season, a felony assault conviction kept his career on hold for three years. He’s since worked his way up to Double-A, where he struggled mightily during the regular season. He bounced back somewhat in the Arizona Fall League, making it a tougher decision.

Robinson is the definition of a flyer prospect now, where the talent that made him a top prospect at 19 years old is still there but also concerns about his ability to put it all together. In terms of the mental part of the game, he’s made significant improvements and it’s now just putting it all together on the field. A strong 2025 season could write one of the more compelling comeback stories in the organization’s history.

Should the D-backs leave Robinson off the 40-man roster, there’s a decent chance he could get selected. However, there’s a strong possibility that he will fail to make the Opening Day roster for the team that selects him and be returned. That process played out similarly with Deyvison De Los Santos and the Cleveland Guardians.

In an unscientific poll of D-backs and Pipeline writers who were there for the Arizona Fall League Championship, it was 6-1 in favor of leaving Robinson off the 40-man roster and leaving him unprotected.

No: Me, Jim Callis, Alex Weiner, Jack Vita, Jesse Friedman, Jesse Borek
Yes: Jim Marshall

Related: Kristian Robinson makes his case

INF/OF Tim Tawa

Despite stalling in Double-A the past couple of seasons, Tawa finally broke through in 2024. In 142 games between Amarillo and Reno, he hit .279 with 31 home runs, drove in 90, and a .868 OPS. FanGraphs calculated his production to be more than 30% better than the average hitter in both leagues with a 131 wRC+ in AA and 139 in AAA.

Tawa didn’t rank on any prospect list entering the 2024 season, although he’s a first-time eligible player after getting selected out of Stanford in the 11th round of the 2021 draft. He’ll turn 26 not too long after the 2025 season starts.

If Arizona leaves him unprotected, there’s a good chance he gets selected with better sticking power than Robinson. He’s a multi-positional defender, spending time at second, third, and all three outfield positions. While not necessarily a super utility player, he can fill in at a handful of spots. That would make him useful as a right-handed hitting bench bat. Essentially he’s the ideal candidate for a 26th man on the roster.

I personally think it’s no worse than 50/50 odds that the D-backs will add Tawa to the 40-man roster. There’s a good chance he could contribute to next year’s squad as emergency depth.

LHP Kyle Backhus

Backhus is an interesting decision. A year ago, it felt all but certain he’d get his first MLB opportunity in 2024 but it never happened. While only limited to 35 games in Reno, he pitched to a solid 3.94 ERA in the tough Pacific Coast League.

Backhus is a lefty with a dropdown arm angle with the classic sinker/slider combination. For better visualization, imagine a mirrored version of Ryan Thompson. Ideally, Backhus will have the same success in Arizona like Thompson.

Further complicating the decision is already the sheer number of lefties on the 40-man roster. They have A.J. Puk, Joe Mantiply, Kyle Nelson, and Brandon Hughes. Nelson and Hughes are non-tender candidates, something I’ll do a deeper dive on later this week, the former missing the majority of the season with thoracic outlet surgery and the latter relegated to low-leverage situations.

Should the Diamondbacks elect to leave Backhus off the 40-man roster, it’s almost a certainty he’ll get snatched up with a career 3.74 ERA in 45 2/3 innings at the Triple-A level.

Unlikely to be taken but could contribute to the 2025 D-backs

OF A.J. Vukovich

Originally drafted as a third baseman, Vukovich has become a full-time outfielder. He was finally promoted to Triple-A at the tail-end of the 2024 season. In Amarillo he slashed .270/.342/.458 with 17 home runs and saw his walk rate climb to a career-high 9.4% in 121 games. His reward was playing the final week of the Triple-A season.

Vukovich comes with big swing-and-miss and plate discipline concerns, which we should have more data on with more games played in Triple-A. He’s athletic enough to play the outfield, preferably as a corner outfielder that can play center in a pinch. He’s very rangy and runs well underway, so he should handle the tough outfields of Chase and Coors well enough to get starts.

However, the concerns about the bat make him more of a 4th outfielder profile. He saw his numbers against lefties improve in 2024, hitting .323 with a .938 OPS in 134 plate appearances. However, it also comes with a fairly low walk rate of 7.4% and a strikeout rate of 27.4%. If he can repeat this performance against lefties in Triple-A, then I feel more comfortable projecting him as a 4th outfielder. As an actual outfielder who can do damage against lefties, he’d make the ideal 4th outfielder in Arizona in the future.

C Caleb Roberts

Roberts is probably the least likely candidate to be added to the 40-man roster but he makes for the ideal third catcher. As a left-handed bat who can moonlight at first base and the corner outfield, he is an end of the bench player who is better than most emergency catchers.

After back-to-back solid seasons in Double-A, it’s almost certain Roberts will get an opportunity in Triple-A in 2025. He’s not quite as good a bat as Adrian Del Castillo, but if there’s a chance he can stick behind the plate, he still has utility to a big league club.

RHP Austin Pope

Pope was a guy who I was sure was getting taken in the Rule 5 Draft last winter, but he wasn’t selected. Comparing things to a year ago, his long-term outlook isn’t much different. He’s an up-and-down arm that serves as useful bullpen depth throughout the season whose 40-man clock hasn’t started.

Pope features a mid-90s fastball with high vertical break numbers with a curveball and slider, he pitched to a 5.72 ERA with an 11.1 K/9 and 5.2 BB/9. His walk rate jumped significantly, as he was at 3.3 in 22 innings. With his peripherals declining somewhat, it’s less likely a team will be interested than they were a year ago.

Minor League Phase Candidates

The minor league phase of the Rule 5 Draft lasts four rounds. Players not on an organization’s Triple-A roster by November 19 would be eligible. The players above are all but certain to be on there, so here’s a list of names that would be possible selections. Most of them coming from Roster Resource’s depth chart on the Diamondbacks.

Starters: RHP Joe Elbis, LHP Avery Short

Relievers: RHP Conor Grammes, RHP Mitchell Stumpo, RHP Jhosmer Alvarez, LHP Liam Norris, RHP Luke Albright

Catchers: J.J. D’Orazio

Infielders: Jean Walters, Juan Corniel, Jesus Valdez

Outfielders: Junior Franco, Angel Ortiz

Michael McDermott has been writing about the Arizona Diamondbacks, and their minor league system, for 9 seasons for AZ Snake Pit, Diamondbacks on SI, and Burn City Sports. You can follow him on X at x.com/michaelmcdmlb or at Bluesky.