Allegri is one of those responsible for this, but it would be wrong to say that all the blame belongs to Allegri alone. The players also make mistakes here. They weren't good enough. They also made critical mistakes in some matches. They also lost points to the teams in the relegation zone in the league. Although they had many opportunities to rest for the championship, they could not achieve sufficient success.
I don't know what happened to Juventus in the last seven matches, during that time they were only able to collect six points. One win in seven matches shows how bad Juventus performance is, Allegri is the party most responsible for the bad results achieved by Juventus recently. Mistakes made by the players remain Allegri's responsibility because he was the one who carried out the plans before the match, such as arranging the formation and strategy in the match.
As a result of his performance continuing to decline, now his position has been taken over by Milan. Juventus position is also increasingly vulnerable after dropping one place, Bologna could be chasing their points and Roma, who are performing very well under De Rossi's management, are also trying to get into the top four.