I agree that he has done poorly defensively. However I'm with Serghei here. Alves has been very useful to us in providing extra outlet in our attack, making him a very valuable member of the first team.
I dunno about you guys, but my understading of our defense since Pep days is completely different. IMHO we never have the best defenders. Think of it realistically; Pique as we know can be very inconsistent, Puyol is great tackler but he is also not the most composed defenders out there and he was also prone to make mistakes. Abidal, well for me he has the composed play style and brilliant ball control, but he never had the aggresiveness of a top top class defender.
BUT at Barca all these flaws are covered up by our defensive system. Our tactic, while giving more freedom to the players when attacking, it also require our players to cover up each other frequently when defending. Thus the case presented by Ursegor is actually very normal in our team. The difference between now and then is actually our inability to close down opponents like the old days.
So my point is, its not fair to point directly to Alves for our wobbly defense. Its the system, which is not as effective as it once was.
But as a member of the team Alves should be lauded for his overall contribution, and that must include his attacking prowess, even though on paper he is a full back.