Is the highlighted defender Peluso? Rubbish graphic, he wouldn't have got anywhere near the ball, and it's not his man. No defender steps backward to defend a ball behind him, it's for those who can see the ball to deal with.
First thing, that's a great cross in. We let Verona do that all game. The best thing to do is stop that at source, but second half we never 'bothered' to do it, and gave away stupid free-kicks. Secondly, Ogbonna and Bonucci both don't come across the meet the ball, they stand still. Ogbonna is the assigned defender of that zone, but Bonucci could also have bailed him out, even if it is unlikely he would have got there first.
The cross makes the goal, but I expect better from us, even if it's just a strong challenge to force a mistake.