Just watched every play while focusing only on Wagner. Doesn't get a lot of double negatives because he doesn't necessarily blow his assignments, but doesn't get double plus very often either. On most of the running plays, he is a quarter second slow to diagnose. He needs to get downhill more quickly. The previous poster was correct, he got caught on the wrong side of the tackle quite often. The biggest reason for this is because he is reacting rather than attacking. He needs to be inside the hole already at the line of scrimmage, not two yards behind it, getting stuck in the wash. I'm not going to freak out about it, because if you're ever played any linebacker, you know it is ridiculously difficult to do. There aren't that many MLB's in the NFL that can do it, and only once every few years does a rookie do it right away. Part of it is diagnosing more quickly, and part of it is downright guessing correctly.
He made a FANTASTIC play on a Harvin sweep. Diagnosed it instantly, got downhill instantly, and blew it up two yards into the backfield. But on the running plays up the middle, he tends to hop and stop and read rather than attacking at the snap.
A few times he got full extension and got off of blocks quickly, but too many times, he played too high and allowed the blocker to get into his body.
The speed is there. He can go get it. No question. I still just don't know if he is built the right way to stuff the run right at him. The really great news with that is that there are far more teams that are better stopped with speed at LB than those that are stopped easiest by power. SF is really the only playoff team that could really expose Wagner, and maybe Chicago. Hopefully he gets more sand in his pants this offseason and can change his pad level a bit. I have no doubt he'll start to diagnose more quickly.