From what I read on their discussion board, they were VERY impressed with Mathieu at the scrimmage. On the other hand, the reaction was not so good on Walker. Plenty of reference to him being in far better physical condition, but the consensus seemed to be that he looked like an offensive non-factor. King was barely mentioned.
Granted, it was just an intra-squad scrimmage, but if guys can’t score in that scenario, that’s probably not encouraging.