It looks like a few missed and/or simply inadequate coverages and the inability to get to Hoyer eventually led to the TD. On the last play of the drive, the Browns put 3 receivers on the right side of the line, obviously (in retrospect) to isolate their TE in single coverage on the left.
Here's the pre-snap look. Harrison Smith has crept up to the line at top left, across from the TE.

The ball is snapped. Smith lets the TE get a clean release and it's basically over at that point.

Smith trailing the play. he won't be able to catch up.

The TD.

Hoyer looked at the TE all the way. There was never any intent to go anywhere else. If Smith had just jammed him at the line, that might have been enough to force 4th down. Oh, well...