As for the play itself, Byrd takes off on a go route. Thompson sees that UAB is singly covering Byrd and takes a shot down field. That's the best part of the play on Thompson's end; a UAB defensive back can't cover Byrd in single coverage, so Thompson made the a good decision in throwing downfield. It looks like what happens with the safety is that he's spying on Justice Cunningham coming over the middle of the field until Thompson lets the pass rip. By that point, obviously, it's too late for the safety to make it to Byrd before Byrd makes the catch. The other key to the play is that the UAB corner falls down. I'm not sure if the corner would have been able to contest the play either way, as he falls right as Byrd goes past him while hitting fourth gear. If the two players got locked up somehow, give Byrd credit for keeping his stride and making the catch. Thompson also deserves credit for a very well-placed deep ball. Given the lack of safety help, Thompson was at liberty to lift his throw a little, which made it easier for Byrd to adjust to and haul in. After the catch, the rest is history given Byrd's blazing speed.
I included this play in the countdown mainly because it made the record books as the third-longest TD pass in Carolina history. The first two were both in 2003, 99- and 98-yard hauls by Troy Williamson and Matthew Thomas, respectively.
The play couldn't be higher because while it did get a blowout started in earnest, this game was against UAB and in the end wasn't very close, and I'm reserving the highest slots for the big plays in close games and against good teams.