After the World Cup final Webb said he had seen what Nigel de Jong did but did not want to send him off so early in the match. This was the world Cup final and this match was different from all other matches. So the rules were a little different too. Good decision, I think, sending off a player in the first half would have ruined the match for a billion viewers. Nigel de Jong could always be locked up after the match.
This match though was just a Champions League group stage match, there are a couple of hundred of them each year (so it seems), nothing special. So there was no excuse for not sending off Ibrahimovic and perhaps Inzaghi.
Webb and his team were sent home in 2008 for allowing an off side goal to Poland. In this match there was a similar situation. We should alway be careful with accusing assistants: it's often really hard to watch both the player who shoots and the player who will receive the ball at the same moment. But, man!, this situation was easy to see, like the one in 2008. There is no excuse at all.
When we started this site in 2005 there were many great European referees, most of them are retired now. We still have Busacca (thank god ;)), Larsen (one more month) and Frank de Bleeckere. New great ones still have to prove themselves. Kassai, maybe, but Brych, Cakir, Kuipers, Rizzoli? Sure, good refs, but not (yet) great. Webb looks like a great referee, but he really makes too many important mistakes.