The best receiver in the NFL was just traded ... for a 28-year-old running back!?!?
Yup, that just happened ... DeAndre Hopkins was sent packing from the Texans to the Cardinals for David Johnson -- and it's got everybody wondering, WHAT THE HELL IS BILL O'BRIEN DOING?!
The stud receiver -- a 27-year-old, 3-time All-Pro who was on a VERY team friendly deal -- was traded along with a 4th-round pick just minutes into the league's legal tampering window Monday.
And, in return, O'Brien's Texans reportedly received Johnson, a 2nd-rounder this year and a fourth-rounder next year .