Back in the day there were players who spent years in the PCL or with some Class C ball team where they hit .355 and won championships and had fan clubs and I can imagine life being pretty good even if they weren't in the majors. Now you have to go overseas to do that, and people mock you from their Cheeto-littered couch for not being a Major Leaguer.
Mullins plays legitimately good CF defense. The arm is subpar but his range is upper tier and he catches whatever he can reach. For me he’s a nice 4th/5th OF to have around to play late inning defense, pinch run, and start a bit vs. RHP.
His bat is spotty, but I’ve seen worse in a plus defensive CF. Steamer and Marcel project him at .693/.694 OPS which seems like a good projection to me, though he might do a bit better if they keep him away from LHP better.