I've been kinda down on Mitchell, maybe unfairly.
First, his defense gives him a high floor and it's easy to see him becoming, at worst, a fourth/fifth outfielder that can play center very well. That's valuable in itself.
Second, I was recently listening to MKE Tailgate's minor league report and the guest mentioned that Mitchell's swing decision peripherals aren't aligned with his results (ie. he looks worse than he has been). He's not chasing a ridiculous number of pitches and he's not missing a ton of pitches, the sequencing is just killing him.
I haven't had a chance to dig into this yet but plan to do so.