He was never, ever, ever better than Lehman, it was a case of his contract was up, Wenger didn't want to renew it and he wanted Almunia to start playing more before Lehman left, Almunia never looked close to world class, he looked like he might be half decent till we found a world class keeper for about 6 months, then it became clear he definately wasn't, what 4 years later and Wengers only just about noticed and is doing his hardest to do as little as possible as slowly as possible to get a better keeper in.
For a guy who at the end of the last season admitted a new keeper is required, two bids for a keeper with at best 2 seasons left, 2 months apart is about as little as you can do.