Depends on where that player plays. I always put my skill points on defense & physical when dealing with a DMC,DML,DMR,DR,DL,DC & GK. And I put all my skill points on attack & physical when dealing with MC,MR,ML,AMC,AMR,AML & ST.
That's OK, until you reach the maximum difference of quality. Sooner or later, you HAVE to allocate attack points to defenders and vice-versa.