I wouldn't have thought a re-direct would have been the sole culprit. And don't forget, there are off-page factors as well, so if Google looks at your links, it may be that they need more work.
Dont forget here that there are 200+ primary metrics that Google look at, and each of those metrics has metrics of their own. For example, I did listen to Matt Cutts talking about this some time ago and hinted that some carry as many as 4000 individual rules. Not saying this is still the case as this was a few years ago, but it makes sense with Google working lots into page quality algorithms, that there are going to be multiple signals that will be triggers.
Hard to go into great detail about the SEO on your site without doing a thorough analysis.
Andy