I think it's more important to think of ratings in terms of how they compare to other players. In the instance of arm strength you give as an example, a 75 Arm RF would be league average or slightly above. 85 would be excellent. 95 is an arm you'd likely see only on a SS.
The other consideration is that very few ratings are definitive by themselves, they all seem to affect player performance in combination with other related ratings. Part of this game it seems to me, is learning or guessing which ratings work together.