Thielen's success has very been surprising, given the fact that he's a white UDFA and the Vikings drafted Laquan Treadwell (called the most "NFL ready" WR in the draft) in the first round and have other black veteran WRs such as Johnson, Patterson, and Wright. The usual caste protocol for a guy like that is to have him wallow in obscurity for years, abuse his body on special teams, torture his psyche by constantly cutting/waiving/releasing him, and permitting every black WR to play ahead of him on offense.
If Adam achieves a 1,000-yard season, it'll be every bit as shocking as when Gary Barnidge came out of nowhere last season.