He's definitely not throwing a "key" block, he's in the game to block no different than the men before him (Coleman, Smith, Kirkwood etc) he has no impact as a receiver but for the sake of looking multiple he comes in to block.
I remember the way Payton used Coleman. He would block almost every snap he was in there, and when the defenders got tired of him and just tried to avoid him... bang! Payton called his number. Smith was used the same way. Too bad they were injury-prone/couldn't catch.