BMI can only be used on the general population as an average... Not anyone athletic. It also geared towards 'lightweight' athletes, like runners, cyclists, etc.
I'm 183cm, and 90 kg. So i'm 26.9 on the BMI scale. It doesn't take into account body fat. Hell, Schwarzenegger was 6'2", and had a competition weight [what he would appear in photos, and on stage] of 235# [~107kg], so that would make his BMI 30.2 ! Let alone if we factor his off-season training weight of 260# [~118kg], which would make him 33.4 !
It is quite obviously flawed.
The only thing to care about is overall bodyweight in relation to body fat percentage. Typically, men see abs/etc at around 10%. Though, of course that varies as to where they carry thier weight.