It's actually pretty interesting how fast a team of players can implement a new system with proper coaching. In 2016 Conte switched to a 3-4-3 during the last 25 mins of a game vs Arsenal. Granted, that side had some pretty good players. This is what Conte said in 2016:
Antonio Conte has explained what prompted him to change
Chelsea's system following damaging defeats to title rivals Liverpool and
Arsenal.
The Blues enjoyed an impressive start to life under Conte, winning three and drawing one of their opening four league games while generally lining up in a 4-3-3 formation.
Summer signing N'Golo Kante was tasked with shielding the back four with two of midfield trio Nemanja Matic, Oscar and Cesc Fabregas playing in front of the France international.
But a 2-1 home loss to Liverpool and the subsequent comprehensive defeat at Emirates Stadium in September prompted a reshuffle.
Though at that stage the game was beyond the Blues, Conte ordered his XI into a 3-4-3 formation for the final 25 minutes at Arsenal and has not looked back since.
Chelsea have recorded five straight Premier League victories without conceding since, scoring 16 goals.
Conte told the club's official site of his decision to change formation: "We started the season with another system because the idea in my mind was that I wanted to play with the 4-2-4, and then we switched with 4-3-3 and we played also in the same way like last year, 4-2-3-1.
"But I noticed in some circumstances we didn’t have the right balance because when you concede more goals than your opponent and even more chances to score a goal, it is never a good thing. For this reason, we switched to the new system of 3-4-3 and I think this is a good fit for our squad because also we have the strikers adapted for this system.
"I thought it would improve us offensively as well as defensively and we didn’t lose our offensive situation. In this way we have increased it because we scored many goals and created a lot of chances to score the goals and also if you maintain the clean sheet, I think this is the right way."
Btw, Conte had been at Chelsea for 5 months, when he decided to change the system.
Amorim has been at United for what, a week? Some peeps need to calm down a bit.