i duoed with a friend (i mention this because i don't think we were up against a full 5) and we ended up fighting a protect the vayne comp. i went godlike by midgame as kog so i figured we had things in the bag but vayne got a few kills (not too many--maybe 3 over the course of 10 or 15 minutes playing cleanup crew) and their team went full peel mode. all of their effort went into protecting her. even with nobody diving me we couldn't nuke her down. once they started winning teamfights she started snowballing and we ended up losing. first time i'd encountered a protect the X comp -- pretty frustrating.
with that being said i hear a lot about how she needs to be nerfed and despite having won lane against vayne many times only to lose the game i don't think that's the case. they already gutted her last year and i think she just places the burden of shutting her down on your team as a whole