Reckon far too much importance is thrown at starting formations and how the eleven line up on paper with the way the game is played these days.. Most teams have different shapes for each phase of the game (in possession, out of possession, and in transition - broadly speaking) and there's a whole host of analysis on how the likes of Liverpool and City build from the back with 3 (using lopsided fullback positions or dropping the DM between the CBs). I saw an article once where a player talked about how, within a single game, Man City would be likely to use 4 or 5 different configurations while trying to break down teams under Guardiola. I think it only makes sense that you want your squad to be adaptable to at least a few different systems in order to be able to make a difference tactically and to give the opposition more difficulty.
As for Lampard, having followed him closely at Chelsea, one measure I definitely felt was that he liked to revert to the back 3 whenever we faced big teams or if we wanted to match up with an opponent using a back 3. I don't think it made us any less potent on the ball and I vividly remember dominating Spurs (twice), United, and Arsenal amongst other teams using that system in his first season.