And prior to the ill-fated 3rd-and-1 delay of game late in the fourth quarter, Williams had run for five yards to set up the short yardage situation before being taken out.
The substitution pattern flowed more smoothly against the Eagles as Renner threw for 227 yards and two touchdowns and Williams ran for 55 yards and a touchdown on seven carries. Williams also completed four of his eight passes for 55 yards and a touchdown, while Renner was sacked four times and accounted for minus-22 rushing yards.
"Any time you're moving the chains you're going to have a better rhythm," UNC head coach Larry Fedora told reporters during his postgame press conference. "I've got to give both those quarterbacks some praise as far as how they're handling the transition between the two.
"A lot of people are going to tell you that you can't do that, that it's going to mess with the flow of the game. But they're really doing a great job. It's a very seamless transition between the two. They're very comfortable with it."
Renner agreed with his head coach, adding that increased reps during practice emphasizing the in-game substitutions have been invaluable.
"It keeps you in the game," Renner said of the rotation. "When he's on the field, I'm watching and when I'm on the field, he's watching, so we can feed off that energy. It worked out today."
On UNC's first possession, Renner connected with Ryan Switzer for a 13-yard touchdown pass. Williams entered on UNC's fourth series after consecutive three-and-outs and led the offense on a massive 15-play, 81-yard scoring drive that culminated with a 1-yard touchdown run by A.J. Blue.
Both quarterbacks participated in UNC's sixth possession, which ended with another touchdown – a 10-yard pass from Renner to Bug Howard – to cap an 11-play, 90-yard drive.
UNC's third quarter possessions were less rhythmic, with each quarterback bearing responsibility for a three-and-out near midfield. On UNC's final series of the quarter, however, Renner connected with Eric Ebron for two passes that went for a combined 50 yards before Williams found Howard in the back of the end zone for a 17-yard touchdown pass.
The duo traded roles on UNC's opening possession of the fourth quarter. Renner rushed for 17 yards and Williams followed with a 16-yard completion to T.J. Logan on a swing pass. Williams capped the drive with a four-yard touchdown stroll up the middle to increase the Tar Heels' lead to 34-7.
Renner and Williams combined to complete 22-of-29 passes for 282 yards and three touchdowns, while rushing for 33 yards and a touchdown.
For Williams, his focus has been on accomplishing the task at hand while avoiding any potential controversy in taking reps from a three-year starter.
"I just have to do my job," Williams said. "Coach is always talking about there's a job on the team that you have to do. I'm not trying to step on Bryn's toes because, like I tell [people] week in and week out, this is Bryn's team and I'm behind Bryn 100 percent.
"When it's my time to go, I have to be ready to go. I have to keep feeding off the positive attitude that Bryn brings to me and I have to give him positive attitude."
If the quarterback rotation has done anything, according to senior tailback A.J. Blue, it's improved execution through competition.
"I think they've humbled each other," Blue said. "Obviously, they both are great competitors and they both can help us win. So when Marquise comes in and does something great, Bryn's like, ‘Okay, now I have to do something great - I'm humbled because I know that if I don't do something great, then ‘Quise could possibly come in.' I think it's a friendly competition going on, but it's helping the offense."
The sum of Saturday's total may have overshadowed Renner's career achievements. He became the third UNC quarterback in school history to cross the 8,000-yard career yardage mark and moved into the ACC top-20 in that category. Renner's two touchdown passes jumped him over Florida State's Chris Rix and N.C. State's Mike Glennon for ninth in career touchdown passes in ACC history.
Renner, however, told reporters he wasn't aware of the career marks. His focus is on the final five games.
"I think we have a lot of football to play," Renner said. "My goal is to get this team to a bowl game. We're 2-5 right now. We have games left to play and we can do it. I think if we continue to focus on one game at a time, all of that stuff will take care of itself."
Renner's 85.7 completion percentage (18-of-21) is the second highest of his career. He completed a school record 95.7 percent of his passes (22-of-23) in his first start against James Madison in 2011.
And while there may or may not be a direct correlation, it's difficult to overlook the fact that UNC had its most effective red zone showing of the season. The Tar Heels scored touchdowns on all five trips inside Boston College's 20-yard line.