I think you're going to see a lot of shorter starts with this group and relying on the bullpen. So, basically a 2017-2019 redux.
Freddy will hopefully be good for 30 starts and 160-175 innings. He's your horse and you gotta cross your fingers that his new S&C program has resolved his shoulder issues.
Miley you have to assume will end up on the IL at some point(s). If you can get north of 100 innings from him, you should be content.
Rea pitched 125 innings last year, so should be able to increase to 140-150. However, he went longer than 6 just once....
Ross has pitched 17 combined innings the last two years. While I think we're going to get decent rate stats from him, I doubt he'll be able to go more than 70-80 innings at most.
Gasser has gone 135 innings the last two seasons. If he holds up well in the transition to the majors, you should be able to get him up to around 150 innings. He ran up some high pitch counts earlier in the season, but went 6 innings in 5 of his last 7 starts. Would be awesome if he's able to keep that up.
DL Hall and Aaron Ashby are the two wild cards. Provided Ashby is healthy and his stuff his back, would be ideal to have them both start the season out of the bullpen providing multiple innings after Miley, Rea, and Ross. Goal would then to be to gradually increase their workload to where they're able to go 4/5 innings and transition to starting if necessary. Rays have utilized this strategy well, particularly with Rasmussen.
In the minors you have McKendry and CRod. Presumably McKendry would be first up, with CRod maybe becoming an option starting in May/June. Both have been stretched out for 120 plus innings.
Overall, I think we should be in decent shape even without an external addition, but it's going to have to be in a far more creative fashion than we've become accustomed to the past couple years and in line with what we saw from 2017-2019. Going to have to ride the bullpen quite a bit. Thankfully, we're returning everyone from what was the best bullpen in baseball last year.