Well, he ran 4.85 give or take a couple of hundreths at both the Combine and his pro day. Nobody's going to confuse him with Vernon Davis, or Finley for that matter. I guess they liked his hands and his size; I guess they reckon they can teach him to block. Some blogger of note, I cannot remember which, had Rodgers' blocking in his plus column for the Tennessee game, raving in fact. He might have a decent block or two I missed, but he had a couple of bad ones I didn't.
Perhaps we should just say he's an inconsistent blocker at this time, perhaps from lack of use in college or perhaps because he just is. It's early. Answers must emerge in their due time when it comes to these unknown quantities.
I think it is safe to say he's not one of those TEs everybody seems to want per the current fashion who will be able to go outside and run receiver routes downfield. That's nice to have, but hardly necessary for winning.