Baseball is a two dimensional sport in which players need to play both defense and offense. In fact it is the only sport in which the defense controls the ball. Heck, unlike other sports, most of the highlight plays are defensive. For a player to be considered great, they have to excel both defensively and offensively, with pitchers being the one exception, and why I would never consider a life long DH among the best of all time.
If one dimension really shines above the other, then they can get buy with the other being sub-par. Ozzy Smith is in the HOF for defense and there are many other players that got in for offense, but they are the best of the best at those respective dimensions.
When comparing players at any time to determine who is better, you have to look at all of their abilities and what they bring. IMO, if a player is in the top in all five aspects of the game and a second player is slightly better in just three and much worse in two, then the first player is better than the second.