Ok. You have bought first-class players, you have chosen a perfect formation, but it just does not seem to be working properly. Maybe it is because you have not put each player to his correct position on the playing ground. Following are basic instructions as to where a player should exactly be playing.

Defense:

• In a defense of 3, you may have your players play in a line or use a sweeper. In both cases the central defender is the most important for the stability of your defense. He needn't be as fast as the other two, but he must score high in positioning. So place your fast defenders as left and right DC (who in most case will be man marking the opponent strikers) and use as your central DC a player with high positioning (he will be doing zonal marking)
• In a defense of 4 your 2 DCs will most likely be manmarking, so they should be fast, with good tackling, marking and jumping. If a DLC or DRC has high acceleration,pace and crossing he is more likely to be used as DL or DR, whereas if he scores well in marking and tackling he will perform better as a DC

Midfielders

• Players with high acceleration, pace, stamina and crossing who can play in two positions (e.g. MLC) are better used as wingers than as MCs. If they score high in attributes like marking, passing, creativity, they are better off as MCs (or AMCs, or DMCs)
• If you are using some sort of 4-1-3-1-2 or so, then you might be using a DMC both in the MC and in the central MC position. In this case the DMC with the higher defensive skills (tackling, marking, strength, staming, jumping) should play as DMC and the one with the higher attacking skills (creativity, passing, long shots) should be placed as MC

Attackers

• Among your attackers the one with the highest heading, jumping, finishing and strength attributes should be placed in the middle of your attack (especially when using 3 strikers, such as in 4-3-3) and often you can make him move a bit forward in the with ball option whereas the ones with higher acceleration, pace and long shots should be placed to the left and the right.

General
It is surprising how many CM fans do not know those basic soccer rules!

• A left-footed player will in most cases perform best on the left side, and vice versa
• In free kicks, a left-footed player is fit to shoot from the right, and a right-footed from the left.The same applies to corners.