My perception in watching it was that Wallace had just come out of his break, and the ball was a bit behind him and surprised him when it arrived, which made it a tougher than average catch. That said, Wallace doesn't seem focused in general IMO, so it's tough to tell how much blame to lay on him for a play that looks like that.
Really I don't even think that play should've been called. Having gotten into FG range where the team could've gone up by three scores, Sherman should've been calling run plays and designed roll-outs for comeback routes on the sideline. Ultra-conservative stuff.
This team doesn't have the kind of quarterback that can outduel other QBs, especially Tom Brady. When you're in position to go up by three scores in a game you should lose, you do everything possible to keep that scenario intact rather than squandering it. The team should've been running the ball and throwing high-percentage passes on plays designed to minimize the possibility of a sack.
Same thing should've been going on at the end of the Buffalo game, but Sherman doesn't seem to appreciate sufficiently: 1) the game situation, or 2) the quality of the personnel he's using.