Yes, Mexes was missed. The defence was completely outclassed. Roma did carve out a few opportunities but their finishing was woeful. Mostly they just ran out of ideas and couldn't come up with a final pass. Lots of long-range shots (Totti, De Rossi). Vucinic was totally out of it.
I'd say it was more a case of Roma imploding than of Inter running riot. Mentally they checked out and those goals early in the second half came like a flood.
At least that's what I remember. I've tried to block it out of my mind, honestly.