Handanovic is not good at 'reading the play' in a way that a lot of the more modern goalkeepers more. For example, there is no doubt in my mind that a goalkeeper like Allison would know how to deal with these type of passes - not specific to this situation but in general. Most goalkeepers today have a higher 'starting position' in order to cut-out counter-attacks, etc. but Handanovic has never really been good at this. The majority of the time he comes out there's a fear he'll make a mistake - I can't recall the situation but I remember something similar against PSV a few seasons back when he could have gotten a red.
No doubt other GKs can make these mistakes, but ones like Alison are typically well-positioned and have better decision making in this type of cases.
Handanovic still has good moments, but he's not really the same player who can bail us out in many games in a season. He'll have a game like the one vs. Napoli every once in a while, but those days are much more rare for him nowadays.