I've got Mesa in my franchise as well. First season, I've got him in AA and he's hitting .244 in June after a very slow start.
I have no intention of pushing him to the majors until at least May-June 2020, and only if he's on a hot streak in AAA.
Important to remember that in real life, sometimes prospects hit their potential, but often times they don't.
I think Mesa's scouting report re: his offense, really reflects what both of us are seeing:
"Scouts are less certain about Mesa's offensive upside. He makes consistent contact, but he doesn't drive the ball much with a relatively flat right-handed swing and he puts the bat on the ball so easily that he doesn't walk much. He could wind up as a faster version of Albert Almora and may not require much time in the Minors."
He's also hitting .227/.273/.247 in high A IRL.