My 2 cents in the debate:
Kiermaier should play excellent defense and has an 80% chance of being a slightly below average or average hitter this year. No chance he's better than that, and 20% chance he has a crappy offensive season.
Bellinger will play excellent defense and has an 80% chance of sucking balls hitting, maybe a 10% chance of being "good" and a 10% chance of magically returning to a beast at the plate
/opinion based on a combination of stats and gut feeling