Lack of any reasonable tight end was poor roster management.
Some injuries (Andrews, Develin, Wynn) can be explained by bad luck. Brady is the big unknown, in terms of how his injury trickled down to effect everyone.
Gordon’s suspension was certainly possible if not likely, Edelman’s age and usage were concerning and injuries not surprising, and Brown’s overall psyche was a risky deal.
Sanu was an atrocious trade. I don’t care if he was “banged up.” He was the most inefficient veteran receiver they’ve ever had and was even worse by the eye test.
Some of this is hindsight, and some of it is due criticism. Having a rock bottom tight end is easily the most obvious mistake and the disaster there was inevitable.