My experience with the game showed, that driving is a good skill for all positions. Shot Blocking is not worth training for Guards, but a nice to have.. a 6or7 shot blocking guard blocks the ball every second game in my league.
You mix things up, Jump Shot is different than driving.. If you have guards with high passing, id rather train jump shot for big man than driving, no passing around i would go for driving and jumpshot. It still remains, ID, IS and Rebounding are the most important skills for bigmen, if you also have jump shot they are even stronger.
I think driving will gain importance, as soon the tactics isolation play is avaiable..