Few things.
1) Passing. Terrible. I watch a fair amount of football and can comfortably say that out of all the sides which can consider themselves huge (in terms of fan base), we have the worst passers of the ball. The amount of times Felipe Melo gives possession away inside our own half because he's trying to be clever is really starting to irritate me, but most of all the poor passing is largely down to the fact that once a player gets the ball, he has to pull off an exact pass to his teammate otherwise he will not succeed, and this is down to movement.
2) Movement. The little movement which our team does is atrocious. I have no idea why nobody makes space for themselves when not in possession, Udinese do it very well which is why they can set off Isla running down the right wing often during a match and they can create so many chances. Juventus players strictly stay in formation which is why the team can never effectively retain possession for long period unless aimlessly playing it square along the back four. This problem has been present since the Ferrara days as well, and back then I was wondering why the hell nobody was bothering to do anything about it.
3) When Udinese equalized with Juventus, they continued to be the dominant team and the Juventus defense was constantly pinned back into the area with players like Isla and Sánchez threatening. It's odd considering that we're the team that is aiming to go to the Champions League while they're the ones who are actually one of the surprise teams of the season. And then the whole attitude of the Juventus team changed once they got their second goal (not after their first), as if we were content to be drawing with Udinese at home? I mean, even Sissoko was brought on for Aquilani, I don't exactly know how that is a positive substitution, reminds me very much of the Ranieri days. The mentality of the whole club has changed when the team doesn't go out to win a game (AT HOME) when it's 1-1, but only get their asses in gear when they're losing to fucking Udinese.
Quagliarella and De Ceglie don't change the attitude of the whole team to perform better, the problems are more complex than a casual 'injury crisis', even though it has contributed.