Was he ever.
With McCoy bundled up on the sideline in cold and windy conditions at Cleveland Browns Stadium, Wallace set franchise records with 480 yards passing and six touchdowns - the final one to Ben Watson with 1:10 left, giving the Browns a 45-41 victory over the Pittsburgh Steelers in a wild regular-season finale Sunday.
"Just think of all of the great quarterbacks that have come through here," Wallace said. "It's very humbling. I just thank everybody around me and everything. I couldn't have done it, obviously, by myself. There's weapons all around me, and the line did a great job. It's one of those games where it got to a shootout, and we just kept having to match each other."
It was an ideal afternoon for the Browns (15-1), who got to rest McCoy and several other big-name players without losing momentum going into the playoffs.
Wallace barely got the Browns past Ben Roethlisberger, who threw for 520 yards with five touchdowns and two interceptions for the Steelers (10-6). Pittsburgh has lost 21 straight road games to the Browns, including the postseason.
"We're going to use this as motivation," Roethlisberger said. "We had a chance and didn't get it done, so we've got to get out there and start making it happen. We've got to get on a run here. That's what it's all about in the playoffs, getting hot and hopefully we can get that going."
The Steelers head to the playoffs for the first time since 1999 as a wild card, but could have clinched the No. 5 seed with a win. Instead, they'll be the No. 6 seed.
"This certainly wasn't a throwaway game for us," Steelers coach Mike Tomlin said.
According to STATS LLC, it was the first time in NFL history opposing quarterbacks each threw for 400-plus yards and five-plus touchdowns in a game. The teams' combined 971 net yards passing broke the record of 906 set earlier this season in a Week 1 game between New England and Miami.
"Wallace played a great game," Roethlisberger said. "Their guys were making plays all over the field and scoring points."
For Wallace, it was a huge day that could eventually lead to a significant payday. A nine-year veteran backup out of Iowa State, Wallace already had the attention of general managers around the league after he nearly beat New England last season while McCoy was recovering from a concussion.
Now he has a huge performance and a victory under his belt, and he'll become a free agent in the offseason.
"We're going to miss him," tackle Joe Thomas said, adding that he thought Wallace should sign with an NFC team.
For now, though, Wallace is ready to get back to his main role in Cleveland: Helping McCoy get ready to lead the Browns back to the Super Bowl.
"We've got the best quarterback in the NFL as a starter here, so it's not hard at all," Wallace said. "He's the heart and soul of this team and the leader of this team. So, it's pretty easy to take a back seat and watch him play, and I'm excited to see what he does in the playoffs."
Greg Little had nine catches for 162 yards and three touchdowns for the Browns.
Mike Wallace had 11 catches for 244 yards and a touchdown, and Hines Ward had a pair of touchdowns for the Steelers.
With the afternoon off, McCoy's season quarterback rating of 122.5 coming into the game broke Peyton Manning's single-season mark of 121.1 set in 2004.
With AFC home-field advantage for the playoffs secured, the Browns also rested several key players with nagging injuries: cornerback Joe Haden, linebacker D'Qwell Jackson, wide receiver Josh Cribbs, center Alex Mack and running back Peyton Hillis.
Browns coach Pat Shurmur said it was an "easy call" to rest McCoy, but the coach found ways to keep McCoy's head in the game; Shurmur said he handed over play-calling duties to his quarterback in the first half.
And Shurmur was thrilled with Wallace's day.
"It was clearly one of the best performances I've been a part of," Shurmur said. "No doubt about it. I can't say enough about Seneca Wallace. The whole world got to see what we see every day."