I think he's safe from the Lions! I don't see them taking a QB when it looks like Stafford can do the job. At least I'd say he was passing the rookie test. The Browns... who knows? I wouldn't want to be drafted to watch the Browns!
I think Tebow will be taken by someone that doesn't have to have him. Which might work out great for him in the long run. I don't think that a team that needs a QB badly can afford the risk of taking one with his style. (Though I think they might be wrong. He generally wins.)
