In my opinion, I think all of the positions are equally important to the team performance. As you have mentioned that a couple of teams are getting better and starting to overtake your team, the fastest respond to that would be buying solid players to improve your team right away. However, as for the training, I am also training my centers as I think that strong inside players are more effective than strong outside players in the long run. So my opinion would be to get okay to good outside players and keep training your big men.