From 2010-2013, Johnson hurt the Patriots. Over seven games against them, he totaled 31 receptions for 406 yards, with four touchdowns and 24 first downs. His 13.09 average yards per reception in those games highlights one of his top assets -- a catch-and-run presence who can threaten the different levels of the field (short, medium, deep).
For a comparison, let's look at the Patriots' top three receivers from 2014 in that average-yards-per-catch category:
Julian Edelman -- 10.6
Brandon LaFell -- 12.9
Danny Amendola -- 7.4
While LaFell made plays down the field in 2014 -- his one-handed touchdown grab in the AFC divisional-round win over the Baltimore Ravens comes to mind -- he's not the type of receiver who necessarily threatens a defense vertically.
The personable Johnson isn't necessarily a burner, but with his catch-and-run skills he could potentially do that assuming his production drop-off from 2014 was more a result of the 49ers' offensive woes than any personal decline.