From the Shakin the Southland post, “Wide Receiver Blocking Skills”:
… The final concept here is downfield blocking either after a back has broken the first/second layers of the defense or after a completed pass. This is where receiver blocking really is critical. Downfield blocking involves hustle, technique, and recognition. The receiver has to understand what is going on around him to assure that he finds someone to block and takes the correct angle to get to this defender. These are the really big ones that can turn a nice gain into a touchdown.
Like what you see on the play starting at around the 3:25 mark of this clip.