I do think that the tactics are the main reason behind all this (by saying tactics I mean more than just a formation). I think the whole "mentality" thing is blown out of proportion. It's not like our players don't run or don't try to win the game. They're professionals and they're not afraid of Greek champions I'm telling you. They're simply not prepared properly for the game and that's it. I think this Juve team is very unbalanced and that's why it's so hard for us to achieve anything in Europe (where the quality is much higher than in Serie A which means tactical details really matter).
I think it's all about setup. The players started deep trying to be cautious but it's obvious it's coach's instruction to start like this. Conte is Italian, so is Allegri and Italians tend to do so. Look at Roma for example - they tried to attack Bayern from the beginning because Garcia is like this. He's not a defensive minded Italian coach so even though his Roma is an Italian club they're different to us. It's very true that a team is like a mirror of its coach and you have to look at it this way.
The thing is the team Allegri inherited from Conte is a strongly defensive minded one. Allegri didn't make too many changes so it's pretty much still Conte's Juve. Don't be fooled by Serie A performances and average possession against Serie A minnows. Conte was always happy to give the possession away against stronger teams even if those weren't stronger than Juve (like Napoli or Milan). If some have doubts about my statement (that the team is too defensive and unbalanced, take a look at this):
Buffon
Ogbonna - Bonucci - Chiellini
Licht - Vidal - Pirlo - Pogba - Asamoah
Morata - Tevez
That's the formation from yesterday's game. Notice how many defensive and offensive players we usually field. GK + 3CBs + 2 wingbacks that can defend but connot actually attack. When Pirlo is on the field both Pogba and Vidal are very limited in attack because they have to make cover for him (at least one has to stay near him at a time). It often leaves Morata and Tevez left on their own, separated from the midfield. In Seire A it's enough most of the time but in Europe it's too few and that's why opponents get so easy territorial advantage over Juve. 2 CBs, a fullback and a DM usually is enough to cover them, because they're left on their own.
This is Bayern vs Roma (they looked like that, correct me if I made a mistake somehwere):
Neuer
Benatia - Boateng - Alaba
Robben - Lahm - Alonso - Gotze - Bernat
Lewandowski - Muller
I'm not going to compare the teams player by player because it doesn't make sense but notice the fact their team is much better balanced than ours. In our formation you can say we have at least 5 players defensive minded (not counting GK) who don't really offer anything in attack: 3 Cbs + wingacks. You could argue if Vidal and Pogba are offensive or defensive minded, but with Pirlo on the pitch they aren't attacking ones definitely. Bayern has definitely less defensive players but they still have a very balanced team. I count it like this: Benatia, Boateng, Alaba and Lahm are definitely defensive minded but Lahm and Alaba can offer something up front too. They place Robben as wingback (on paper because in practice Lahm is covering his side) and Goetze as CM. It gives them a lot of creativity which we lack, because we have so many defensive players. It doesn't surprise me when I see Juve is not pushing forward after conceding a goal, because we have no players to do it. Who's supposed to do it? All our CBs are slow and unproductive and wingbacks are actually good only at defending. If you add to that Pogba and Vidal having to cover the middle it just leaves Tevez and Morata responsible for attacking.
To sum it up: formation change won't do much if the personnel stays the same. We need to change tactics to take some effect and it includes new players in starting 11. Above all we need to find balance between attacking and defending. Along with it we have to get used to new system. It' not enough to try it out once a month for 15 minutes when you're a goal or two down. Players within the new system have to get new habits because many things they do automatically, they have to know what to do, especially when they're under pressure. Along with those changes the style has to be changed as well. The players have to improve passing and movement first of all IMO. Notice how Juve transitions from defense to attack and compare it to Roma for example. They do it more accurate and way faster than us.
To achieve this things I think we'll need a new coach because I don't think allegri is capable of it. It'd be good if he started implementing something new though. Someone like Bielsa would really improve our attacking game from tactical point of view but also personal. Right now everyone except Tevez is looking for Pirlo which could be difficult to unlearn.
For the moment I see our best starting 11 like this:
Buffon
Licht - Bonucci - Chiellini - Asamoah
Vidal - Marchisio - Pogba
Pereyra - Morata - Tevez
IMO it's worth considering what is unneeded right now to release some resources:
1. A third CB. Especially if it's Ogbonna. It's better to play a compact back 4 because Ogbonna is not really a spectacular defender nor he offers anything going forward. He often plays close to the sideline and I think Licht will do better there.
2. Regista. Especially if it's Pirlo. He's out of form and it seems he's not up for it anymore. He's not offering the service he used to and instead he seems to be an even bigger liability than ever. He should be benched and Marchisio has been in a very good form since the start of the season so that's not a problem.
3. Overall the idea of 3 CBs and 3 CMs on the pitch at a time. It reduces the pace of the team because the players are too close to each other and aren't making runs into holes; That's why we can't counter attack or even make a transition from defense to attack fast enough.
I accommodated Pereyra in starting 11 because I think he's the best offensive player we have on the bench right now. He can make runs and crossing as well as taking on defenders. he's quite a direct and fast player so he really should help there.We need better but for now we have to cope with what we have. The most important thing is to start making changes instead of staying conservative because "we have no options".