Which is more important??

Last season i tried to change the position of many players. Unfortunatly after many many games they didnt reach the best position and i had to change it again... ... So, i lost many games and finish on 4th.

Now I try to buy some players with their natural position already there but my question is: Team Chemistry will make me lose many games again??

Thanks.

p.s. i want to change my Special Team.