Good point. But Moyes could still employ the sistem on the training ground and start preparing a 3rd formation (after de 4-4-2 and the 4-5-1). I'd start with a 5-4-1 or 4-1-4-1 (which I think we often use), to create less disruption in the team's routines and, progressively, change it to the 3-5-2.
Still, I think that we have the right players to do it. We'd have at least 3 players in the midfield and 3 steady defenders (Distin, Jagielka and Heitinga).
Upfront, Moyes could change between 2 strikers or only one with a player like cahill, who could act as the fourth man in the midfield, if needed.
No need to say that Coleman and Baines would be caught out of position fewer times and could go forward with less defensive preocupations.