It pretty much depends on your quality, if your like 10Q better than the rest of your league then playing one formation is fine. This season my best players (quality and rating wise) push me to play 4-5-1 v style, though I have a squad large enough to play most formations. If my quality is a lot better than my opponents I wont try and counter it as there is no need too. Id maybe sell some of your mcs and buy other positions as its unlikely that youll have more than 3 of them injured at one time