Javi Martinez is a huge loss for them. He's very intelligent, almost like Marchisio's evil twin who connects Bayern's back and front line's defensively. He's good at shepherding the opposition around and into his teammates' tackles and he also wins balls cleanly and with some form of elegance like Claudio. He really helps their transition from both phases because of how smooth he is. Gustavo, by contrast, might win tackles but the ball will often not land to his teammates or he can sometimes get pulled from his position.
This is important to me because I don't have much faith in our strikers uncovering themselves from Bayern's CBs, who appear to be a weakness, but because of their athleticism, perform admirably in combination with the rest of their team. The work of their teammates allows them to be shielded and at the same time very aggressive to win balls from behind a forward. It will be like the Coppa Italia match vs Lazio (second leg) where we tried to find our strikers coming back to the ball but instead, were just run through by Diakite and Dias.
Bayern also does not play for offsides so Matri's smarts might be mitigated if we were to prefer him to Giovinco. It looks like, IMO, we will need the goals to come from midfield and possibly even our wingbacks. I think the loss of Martinez in the first game is like us finding a weak link in the fence. We have to attack that section often.
If we try to play like our first leg vs. Celtic who applied pressure non-stop, I think we will be disappointed. There is very little chance that Matri could find that space behind Bayern's defence like he did on his goal vs. Celtic. I would like us to have more of the ball and look to play in our CMs behind our strikers who are checking back to the ball. But it's unrealistic to expect our CMs to make these runs from so far back, that's why we need to have some of the ball and push the play more towards the half-line. We cannot sit deep and counter is what I mean. If we want to counter, we have to at least sit a bit higher up. There is little risk of Mandzukic or Kroos beating us for pace.
A tactic like we used against Celtic will not work, our outlets will just be gobbled up by their athletic back line (did not even mention Alaba). We have to try and beat them with the ball on clever runs that start from good areas, not hail mary's.
It is very reassuring that their trequartista Kroos is not only in bad form currently, but has struggled vs. Italy in the past, and also does not possess the pace or tenacity to give Pirlo any great trouble on counter attacks or while Pirlo is in possession. He is clever, sure, but often I find he prefers to drop out of that area that Pirlo favours, in front of our defence, and play more like a regista.
Also, Neuer plays like a sweeper. Very athletic and smart off his line.
TL
R version: if we bring a deep lying countering tactic like vs. Celtic, we will be disappointed. We have to try and have the ball and at least push back. 45% is enough as long as the play remains higher up the pitch where we can nip them and play in our CMs or wingbacks. I don't think our strikers will cause much damage, despite them seeming to have a leg up technically over their CBs, because their CBs are never left in bad positions vs. strikers. Martinez is a big loss and an area we can exploit in the first leg.