In 2017, Mike Trout had 402 plate appearances over 114 games. For the season he hit 33 home runs, and led the league in OBP, SLG, OPS, and OPS+. His WAR (Wins above replacement) for 2017 was 6.6.
If Mike Trout peaked with seven seasons exactly like 2017, his peak WAR7 (a useful Hall of Fame monitoring stat) would be 46.2. The average WAR7 for Hall of Fame centerfielders is 44.5. Given that the HOF has made some fairly gnarly choices with respect to centerfielders over the years, this would make Trout a marginal case, right in the same area as Andruw Jones, Carlos Beltran, and Jim Wynn.
But of course, we don’t count Mike Trout’s 2017 season in his peak WAR7, because it is now his eighth best season as a professional. Trout’s actually WAR7 is 64.7, ahead of Tris Speaker and way ahead of Ken Griffey Jr. and Joe Dimaggio. It is extremely likely, given that this season is only 2/3rds in the books, that Trout will pass Mickey Mantle for the third highest WAR7 of all centerfielders. It is not out of the question that, in the next couple seasons, he will pass Ty Cobb.
All this is to say that Mike Trout is insane. If you saw Willie Mays play (as my dad did, in San Francisco in the 1960s), then you’ve seen a better centerfielder than Mike Trout. If you didn’t, then you probably won’t.