He's got a long way to go on defense, no doubt. He showed growth his last year in the minors and quite a bit of growth in 2018. Nobody knows, if that will continue going forward, but he's young enough to think there's still time for significant growth.
Devers did struggle at the plate for much of 2018, and he missed some time with injuries, but at his age, that is expected. He has over 1 XBH for every 10 ABs over his short MLB career. That makes up for some of the low OBP, but I'm expecting improvement as he plays at age 22.
Bogey hit .684 at age 20 and .660 at age 21 before jumping to .776 at age 22. Betts jumped from .812 and .820 to .897 at age 23. Jackie Bradley Jr was in single A at age 21 and was promoted to AA during his age 22 season.
He's got the skills and the instincts to be a great hitter. This could be the year, but it may take longer.
To me, it's more about when than if.