As for Diggs its hard to say what is going on as most #1 receivers are prima donnas.
Most of the problem with him is he wants lots of targets and for the first 10-12 games he gets a lot and is usually a league leader at that point.
But he has a small frame and that means he gets banged up and his production rate drops off significantly down the stretch.
Check out his stats from the last 3 years...they show it.
He needs better work load management and to be less demanding on his amount of targets in weeks 1 to 10 to stay productive for 17 games.
His goofy meddling brother doesn't help the situation either
https://bleacherreport.com/articles/...-cryptic-tweet