3 at the back is completely right for this set of players. Chilwell and Ricardo are two excellent players and should be in our team, but both of them whilst great attacking, lack a little defensively. And when they bomb up the pitch, it leaves our two centre backs horribly exposed.
This happened during our title winning season and Claudio then swapped Schlupp and De Laet for Fuchs and Simpson, to keep four out and out defenders at the back. This would completely stifle Chilwell and Ricardo if we kept them permanently at the back, so adding another centre back and having them as wing backs is perfect.