A few things...
-Potential is derived from physical traits. A big, fast, strong, agile athlete has more potential than a less athletic one. Either get rid of the potential ratings or reverse the set up so that the potential rating is based off the physical ratings. For example, when we up the speed, we up the potential.
-If neither of those work, allow us only to adjust ratings within the potential range. For example, A potential allows for max ratings, B potential allows for 89 and lower, and so on.