Allegri has been a great coach for Juventus domestically, winning 5 consecutive Scudettos. Under his management, the club has also been to two Champions League finals, losing both. The fact is that Allegri can't take them to win European titles. You can't expect the same tactic of playing defensively to work against aggressive teams such as Ajax or Liverpool. Even against a not so aggressive team like Atletico, they still blew the first leg. Yes, Juve saved themselves at home but then proceeded to return to their overly defensive roots with no attack during the quarterfinals against Ajax throwing both matches. Juventus does well domestically because they play against like-minded teams with similar strategies. We're not saying it's not okay to play defensively, but when the time comes, Juve can't hold their own against a mainly attacking team and that's a fault of the manager.