Sometimes I wonder if people post opinions like this just to be controversial. Either that, or its the classic old English opinion that's out of step with the modern game. Of course the formation and the system is a crucial factor in success. What formation you use affects your ability to maximise particular player attributes, the relationships between particular players, and most importantly the use of
space, which is the single most crucial concept in football. Tactics are crucial in modern football, and can turn a match, or a season, on a knife-edge. Chelsea if anything have proved this. So did Leicester. So did Atletico. So did Mourinho during his first spell at Chelsea when
his industrious midfield 3 completely overran all other premier league midfields. Formation and shape is crucial, and to suggest otherwise is terribly naive.
Personally, I'd really like us to play 4-3-3, but there are a lot of advantages to 3-5-2. See
this video on the virtues of that system for our key players.