What you see is what you get - that is, with all skills equal - a 5'10" player will play Center just as good as a 7'5" player. However, the effort put in for a 5'10" player to gain - say sensational rebounding - is much greater than for the 7'5" one, cuz he's penalized for his height in training. Thus, people will tend to train high players in inside skills, and low players outside, but it's fully possible to make a 5'10" player a great center.
To sum it up - when you position your players you should look at their skills, not their height.