Others are getting separation. An example at 00;38 in this clip, on a 3rd and 6, Josh is locked on Diggs, who is right at the 1st down marker in tight double coverage and he completes a high risk pass. Yet all alone, beyond the 1st down marker, heading toward the sideline just beyond Diggs is Davis. A much easier 1st down lob.
https://www.nfl.com/videos/stefon-diggs-best-catches-from-100-yard-game-vs-giants-week-6
Then there are several short quick passes to Diggs. Josh was locked in only Diggs only most of the night.