First off, I certainly never make excuses for anyone.
Second, Rui has been our most expensive signing by far + was supposed to pull all the strings in midfield, so of course people tend to scrutinize his performance more than ..say.. Brocchi's.
I don't know about Rui's performance last night apart from the match summary + I didn't watch the replay this afternoon so can't + won't judge on this particular match.
Apparently, after we had wasted the scudetto in 2002/03, he was identified as a bit of a liability (he truly was with his 10 or so assists + zero goals), therefore Kaka's transfer was sped up + since the Brazilian made an immediate impact + delivered exactly what Rui had failed to produce, goals + a speedier build-up, Rui consequently had to acquaint himself with the bench.
This season he has been called up a few times, also to support off-form Kaka', but he rarely impressed IMO. Velocity is not exactly our midfield's most striking feature + all he does is add another dimension of slowness to it. It's a fact, unfortunately. OK, credit for being able to keep the ball when we play that lame type of uninspired possession-oriented football, but that's not his role, his role is to create + inspire + support our strikers !
Taking into account his age + what appears to be a continuous decline of form you don't need to be Einstein to figure his career is nearing its end, at least at Milan.