He ran the play that was called. He doesn't have the freedom to go four yards instead of one before he runs into the flat. That route doesn't call for it to go to the sticks because the idea is that against certain coverages he's open and you get it to him and he can run. That's the call there. The Dolphins ended up having the right coverage called and a guy was right on top of him. He was never going to get the first down with that coverage scheme unless the defensive back just utterly whiffed. The fact that he caught the ball at all was a victory, it's possible Brady was throwing wide since he knew the play was dead anyways.