Lidge as the #3 reliever isn't a big deal. He doesn't have the track record yet.
I personally think Astros fans are way too optimistic about Backe. Just as Beltran shouldn't be overhyped for his playoff performance, neither should Backe's surge near the end of the year. He could easily fall flat on his face this year when hitters get a better gauge at him. I think the Astros would be quite fine with him putting up league-average ERA. Which would mean a pretty low ranking.
Btw, espn.com now pretty much has no good analysts anymore. I wouldn't read much into anything put up on that site, other than breaking news.