A 5 man team?

Just noticed my next set of cup matches and the team I am facing only has 5 players on the field. He has a GK, DC on the right, MC on the left and 2 STRs. He has 6 subs and 3 reserves. If this isn't a bug or glitch I don't know what is, thats the most bizarre thing I've seen on this game. He won his first set of cup matches so im assuming this has to be some sort of exploit in the game.

It is an abandond team. The system fills the field automatically from the bench. If he had subs set those are used otherwise it just puts whoever on. If you can look at a prior match in the Cup you can see formation filled in.