Through their age 28 seasons, Trout is better than Aaron was, and it's not particularly close. Trout's lowest OPS+ (other than his 40 game call-up at age 19) was 168 (9 seasons). Aaron had an OPS+ >/= 168 8 times in his career, only twice from age 20-28. Trout already has more MVPs (3-1), more MVP runner-up (4-0), more MVP top-5 finishes (9-8). Aaron was better from age 29-38 than he was from 20-28, and there is no guarantee Trout will do that (odds are against it), but he has a decent lead right now, and he certainly could end up topping Aaron.