I think another approach is to assign points to certain attributes.
If a guy is 7' and 265'lbs that accounts for 25 points.
100 Speed = 20 points. 100 Shot = 20 points.
And each team can't go over 200 points (or something like that).
That way there is no way you can have a full team of Shaq's with the speed of Kane on one team.
With a Cap on points, teams will be forced to be more versatile.