training out of position is already possible in BB. the problem is that penalties are too harsh so nobody uses it. if you trained passing, training rates should be 100% (PG), 98% (SG), 96% (SF), 93% (PF) and 90% (C), not 100-90-80-70-60 like today. training 100% is painfully slow, so 90% is a big punishment. however, it could be bearable if the tradeoff is playing your center as a center and still getting 90% of the training. that would keep the spirit of training but also allow flexibility.