Even if you think that Watkins is better than his stats because Tyrod, Goff, etc don't get him the ball enough (may or may not be true), the bottom line is, Watkins wouldn't have put up big numbers in Buffalo this year (whether his fault or Tyrod's) and he wouldn't have re-signed, so the trade was a good one for us. Gaines has been solid this year when healthy.
The Benjamin trade looks worse because he has been injured, and even when healthy, wide receivers just aren't an integral part of the offense compared to other teams.