We don't need to change the formation. The problem is that we don't have the right personnel for it, and ironically that is the reason Conte says why he won't revert back to 4-3-3. You can't play a formation which solely depends on your wingbacks who can't put in a decent cross or dribble an opponent if their lives depended on it. Also, as much as we all love Pirlo, we need someone who can replace him next year. He can still cut it in Serie A, but Europe is better. Finally, Marotta needs to spend big in attack and starts to remove the crap we have upfront.
The team is still learning, yeah, but these last 2 performances have been abysmal.