Just thought I'd share a trick that works because I've tested it myself is... Some might know about this, but others wont.
Go into the edit mode (this is not a cheat BTW!) then select the team that you would like to settle at and change their formation. If you want to play as a WF then make sure the formation you make has a WF position, same goes with other positions...
I know this works because I edited the England and Liverpool formation to save me doing it online, then when I looked, the AI use it! They might change the formation at different times in a match, but they always start with the same formation.
I think there's only one problem with this though... You might have to restart the BAL for the formation to take effect. I edited mine before I started BAL.