Of course, there's a good chance Eovaldi spends time on the IL. His history suggests he has a much higher chance than most pitchers, but I still feel like it is hit or miss for 2021. One could argue he is due for a full season or near full season. It's not like he's very old or has had a recent injury that makes me think it will reoccur.
ERod is a tough one to project. While months of bedrest are not the best thing for conditioning, being in great condition is not really needed to be a great pitcher. Yes, it usually helps reduce injuries or the chances of injuries like those caused by running to 1B (his previous knee injury). There are big questions, for sure, but we've heard some encouraging things about his recovery.
Sale seems to have some people like Jacko saying he's toast, while others are hoping for his return in early July and maybe a return to near norm by year's end. The subject has been beaten to death, and nobody can really know.
I agree with Jacko on Richards probably being the best hope of the 4 to stay healthy and pitch well in 2021.
Perez, Pivetta and Houck may be forced to pitch a lot, although Houck's innings will probably be limited to 140 IP or so.
I hope we don't need to rely on Whitlock, Mazza, Seabold, Mata or others for too many starts, unless we are out of it early.