PHOENIX -- The D-backs announced their 60-man summer camp roster on Monday, but there are likely to be plenty of changes to it as the season draws closer.

One player listed on the roster, veteran right-hander Mike Leake, told the club that he is exercising his right to opt out and not play in 2020.

“There were a lot of challenging pieces to put together with the 60-man roster,” D-backs GM Mike Hazen said. “Where is our depth? What positions are we covered in? How much pitching do we have? What positions are we thinner or deeper at? Those were a lot of the factors.”

Outfielder Yasmany Tomas, who is in the final year of his contract and had been removed from the 40-man roster, was not among those in the 60-man player pool. While that could change, it could also mean that his star-crossed career with the D-backs is over.

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The team placed nine of its Top 10 prospects (as rated by MLP Pipeline) in the player pool. The lone exception is top-ranked prospect Kristian Robinson. However, Hazen explained that as Robinson was not able to return to his home in the Bahamas when Spring Training was shut down, he can still work out at the team’s facilities and could at some point be added to the 60-man player pool.

“I would imagine there is going to be a lot of maneuverability as we go through the season,” Hazen said. “There are going to be changes made to our roster [and] we will have the flexibility to do.”

Here’s a look at the player pool as it stands. Players listed in bold are not on the 40-man roster.

Right-handed pitchers (24)

Jeremy Beasley, Archie Bradley, J.B. Bukauskas, Taylor Clarke, Stefan Crichton, Jon Duplantier, Luis Frías, Zac Gallen, Kevin Ginkel, Josh Green, Junior Guerra, Bryce Jarvis, Levi Kelly, Merrill Kelly, Artie Lewicki, Yoan López, Corbin Martin, Keury Mella, Joel Payamps, Hector Rondón, James Sherfy, Riley Smith, Luke Weaver, Taylor Widener

Left-handed pitchers (8)

Madison Bumgarner, Andrew Chafin, Matt Grace, Tommy Henry, Joe Mantiply, Robbie Ray, Blake Walston, Alex Young

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No big surprises here. With Leake opting out, his absence opens up a spot in the rotation that now consists of Madison Bumgarner, Robbie Ray, Luke Weaver and Zac Gallen.  

Merrill Kelly and Alex Young are probably the leaders for the final spot, though Jon Duplantier and Taylor Clarke could also make a push. 

There was going to be a lot of competition for the final spots in the bullpen as Spring Training was winding down, but if the D-backs elect to go with 15 pitchers to open the season, that makes decisions less difficult.  

Of note, the D-backs included some of their top pitching prospects, including the club’s top 2020 Draft pick Bryce Jarvis. While they are unlikely to see big league action the team will go to great lengths to try and find ways to get them simulated innings over the next couple of months to try and build them up for next year.

Catchers (4) 

John Hicks, Carson Kelly, Daulton Varsho, Stephen Vogt 

The D-backs were likely going to carry two catchers -- Carson Kelly and Stephen Vogt -- but it’s possible they could have another catcher travel with the club in case of injury. Taxi Squad players travel with the big league team but don’t count against the roster, and if three players are carried in that group, one of them must be a backstop.

Position Players (23)

Nick Ahmed, Seth Beer, Kole Calhoun, Corbin Carroll, Kevin Cron, Eduardo Escobar, Dominic Fletcher, Jon Jay, Jake Lamb, Tim Locastro, Ketel Marte, Starling Marte, Wyatt Mathisen, David Peralta, Geraldo Perdomo, Juniel Querecuto, Josh Rojas, Pavin Smith, Alek Thomas, Trayce Thompson, Ildemaro Vargas, Christian Walker, Andy Young

Again, no surprises here. There was going to be some competition for the final couple of roster spots when Spring Training was suspended, but with the initial expanded roster, players like Josh Rojas, John Jay and Ildemaro Vargas all likely make the team.

The addition of the designated hitter makes things easier for manager Torey Lovullo in terms of finding playing time for Jake Lamb, who faced roadblocks at first in Christian Walker and third with Eduardo Escobar. It also could open the door for slugger Kevin Cron to make the roster.