The senior defensive end's game-saving sack for an 18-yard loss left the Demon Deacons with an impossible 3rd-and-28 situation and just 0:31 left, essentially securing the victory for Vandy.
The biggest play of the night also gave Commodore fans a glimpse of just how lethal speed can be.
In one of several position changes this past spring, coaches shifted Harrison from strongside linebacker to defensive end, giving them a significant boost in quickness on the line.
"As a coach, you want to get the most speed you can on the field at once," defensive line coach David Turner said. "This is probably more important in the SEC than anywhere else because of the caliber of the athletes."
At 6-4, 254 pounds, no one expects Harrison to bull-rush the hulking offensive linemen lined up across from him. What they do expect is that the speed and athleticism that allowed him to start the previous 18 games at outside linebacker will translate into playmaking ability up front.
"You don't have to be a 280-, 290-lbs. defensive end and you don't have to take on a 300-lbs. tackle every down," Turner said. "It's not always about adjusting to the man lined up across from you. You have to remember that they need to adjust to you."
Proof of the effectiveness of this approach is now abundant in the NFL, where smaller defensive ends like the Colts' Dwight Freeney and "tweeners" like the Ravens' Terrell Suggs have emerged as the most feared pass rushers in the league. So while the man trying to block him might have a 70- or 80-lbs. advantage, Harrison knows that size alone does not give a player the edge on the line.
"There are ways around that," Harrison said. "I can use setup moves, like lulling them into thinking I'm going straight up field and then hitting them with an inside move. Other times I've been able to catch them off guard and run right around them."
At the same time, Harrison is far from content to rest on the laurels of one big play. The native of Marietta, Ga. is first and foremost conscious of the Commodores' need to tighten up their run defense after Wake Forest's Micah Andrews was allowed to run wild last week.
"It's been a huge emphasis this week in practice," Harrison said. "Like the coaches say, it all starts up front. We spent a few hours the other day just working on getting off our blocks." Individually as well, Harrison knows that he still has a lot of work to do before he is completely comfortable in his new position. While it appears he has already developed an effective pass rush, he acknowledges the need to be more consistent with his gap assignments.
"The hardest part for me right now is adjusting to the run versus the pass," Harrison said. "I have to try not to think too much, and just go out there and compete."
His position coach clearly echoed this sentiment. "I think the biggest problem for Herdley right now is Herdley," Turner said. "He has a tendency to think too much and be overly analytical. We've talked about it, so he knows he needs to just line up and play."
Perhaps it shouldn't be too surprising that the biggest problem for Harrison is his overanalyzing of the game. After all, he was selected to the All-SEC Academic Honor Roll each of the last two years.
Luckily, this type of self-imposed obstacle should be fairly easy to overcome as he becomes more comfortable at his new position. The coaches are confident that as a veteran with as much athleticism as he has experience, Harrison will only improve with each game.
If that proves to be the case, then his monster sack on Thursday night might just be a preview of things to come.