I'm not really convinced that every prospect needs "AAA seasoning" or a substantial amount of "AAA seasoning".
Development is rarely linear, where players learn little things and make little improvements at each level, reaching the big leagues as some kind of finished developmental product. Sometimes players are just simply good enough or not good enough. Or, development is essentially stochastic (Arrieta, DeGrom).
Jose Fernandez went from A+ to an immediate big league Ace while improving his peripherals.
Anthony Gose has like, 1100 PA of "AAA seasoning" and he's probably gotten worse.
Pompey is in the big leagues, looking like he belongs, consistently having good at bats, driving the baseball and showing XB pop/speed, and playing good D. Yeah his statistical sample size will be small for MLB, AAA, and AA, but if you take his entire season as a continuity you have a kid who climbed the ladder from A+ and put up an .850 OPS at each level, so he never missed a beat.
I wouldn't start him in AAA as a rule or anything. I could get behind him being the everyday CF as long as LF is filled with a good trade / free agent, and the CF backup plan isn't just a Gose/Pillar platoon. Or, him in LF and a good CF brought in (defense for days).
But they will probably go with Pompey in LF and Gose/Pillar platooning CF.