It's tough. You can really only train 2-3 guys at a time. Which means by the time your bigs are good, it's time to train guards. And by the time they are good, it's time to train bigs again. And heaven help you if one of your really good players gets hurt.
You can't be sentimental about players. I have stuck with some guys for too long just because I drafted them. Tolbert should be my star player. Since he started out with Atrocious stamina, he's never consistently got the minutes to train. So he lags behind all the time.
My advice is to ignore the draft and buy guys off the TL the week after. Buy players that have similar builds, especially similar Stamina. But you don't want one guard with a 6 OD and another with a 1 OD. Either one of them will never have enough OD to be useful or the other guy won't be balanced enough.