Even if the Cardinals can't trade Miles Mikolas, he should not get starts over their young arms
I'll start with this - assuming the Cardinals' are unable to move Miles Mikolas in a trade this offseason, I know that it is likely he will be in their rotation to begin the year, even though I think that would be a poor choice.
If I were deciding who was in the Cardinals' rotation next year, I'd choose Gray, Fedde, Pallante, McGreevy, and Mathews over Mikolas in a heartbeat. If the Cardinals allow some of their contracts like Gibson and Lynn to walk this offseason, they could easily bring in a second starter of the quality of Sonny Gray to slot in there as well. And honestly, I'd be fine seeing what Robberse, Kloffenstein, and Graceffo have over him as well.
Those are eight internal options I think should slot in over Mikolas, and that's not including someone they could sign or trade for this offseason. Mikolas just does not need to be on this Cardinal team anymore, and it is frustrating to see that this two-year extension he received last offseason has been a huge waste to this point.
If the Cardinals want to become a stronger team moving forward, they have to get out of this cycle of overpaying for back-of-the-rotation production time and time again. The only way they are going to be able to do that is by giving their young arms the chance to prove themselves at the big league level, and considering how bad Mikolas has been the last two years, having him step aside to give them opportunites could not go very poorly.
If the Cardinals had young arms that were not MLB-ready, then yes, Mikolas could be the fifth starter and we can just grimace through it. There is no point in throwing arms out there who are not ready and hurting their development. But the Cardinals' now have arms that need big league innings that are being blocked by someone like Mikolas, and so it is time to cut bait, even if it's painful financially. You have to pay him the money anyway, so might as well cut him if there are no takers.