Nothing for a player is affected by what Best Position he has other than the roster sorting option.
He could be listed as Janitor and he'll still train and perform as he would with any other BP.
A lot of successful users track their players using a spreadsheet or other data-manipulating program.  You may want to look into doing so.
                                
                                
                                
                                
                                
                                
                                    NO ONE at this table ordered a rum & Coke 
 Charles: Penn has some good people 
 A CT? Really? 
 Any two will do 
 Any three for me 
 Any four will score 
 Any five are live