Tom Smart, Deseret News
Brigham Young Cougars quarterback James Lark (7) as BYU plays Idaho in the Cougar's final home football game on 2012 Sunday, Nov. 11, 2012,in Provo, Utah.

PROVO — By Saturday night, following BYU senior quarterback James Lark's 384-yard, six-touchdown, zero-turnover performance in his first career start, a bevy of Cougar fans had flooded Twitter, message boards and radio call-in shows — singing Lark's praises and wondering what might have been.

What if Lark had been starting this season instead of Riley Nelson?

"This guy's been sitting on the sideline all year? You gotta be kidding me," tweeted one fan, summing up the view of many.

With the regular-season completed, that leaves a more tangible and salient question — which QB will be the starter when BYU (7-5) plays in the Poinsettia Bowl on Dec. 20 in San Diego?

After the Cougars' 50-14 victory over New Mexico State last Saturday, coach Bronco Mendenhall wasn't ready to answer that.

"It hasn't been decided," he said. "In my opinion, Riley is still our starting quarterback at this point. We might give James an even harder look and I'm not sure yet, it's too early to say, but rather than being forced into making that decision so quickly after the game, I'd really like the tone of what happened (Saturday) to be a celebration of James' commitment to our program, how long he's battled, and how well he did when he had an opportunity. Our decision on what we do will come out later."

Nelson, who is 4-5 as a starter this season, was at Saturday's game nursing a rib injury. He supported Lark in his first start.

The Cougars enjoyed watching Lark make the most of that opportunity.

"It was awesome," said wide receiver JD Falslev, who recorded a career-high nine receptions for a career-high 68 yards and a touchdown. "Not only that he got his first start, but how he played was really, really special. A guy that's done everything coaches have asked him to, a guy that's gone through the wringer a little bit with trying to get some time here and there and battling through practices, then he finally gets his start and he comes out and (plays well)."

Asked if he thinks about how the season could have been different with Lark, Falslev replied, "No, not really. I have Riley's back through thick and thin. Riley battles, and he's our guy. He couldn't play because of an injury and the next guy came in and stepped up and did a great job as well."

Lark said he would not get caught up in what-if scenarios, either. "I'm not worried about anything else. Today was a dream come true. That's all I'm really thinking about."

While New Mexico State entered the game ranked No. 103 in rushing defense, No. 105 in total defense, No. 105 in scoring defense, and No. 112 pass efficiency defense, coach DeWayne Walker had two weeks to prepare for the Cougar offense.

New Mexico State, which was coming off of a bye week, stacked the box, trying to stop BYU's running attack, and Lark capitalized by making throws. Lark completed his first 10 passes, 21 of his first 25, and finished 34-of-50, as he shredded the Aggie secondary.

Of course, he had plenty of help from wide receiver Cody Hoffman, who caught 12 passes for a career-high 182 yards and a school-record five touchdowns. Hoffman became BYU's first single-season 1,000-yard receiver since Dennis Pitta and Austin Collie in 2008.

The Cougars did all of their scoring in the final 2 1/2 quarters. They didn't get on the scoreboard until midway through the second quarter as early drives stalled.

"As an offense, we started off a little slow," Falslev said. "James did a great job of keeping us composed and keeping our minds and our heads in the game. Then we went out and made plays for him. We knew we needed to do nothing extraordinary, just make plays and do our assignments."

The Cougars ended up rushing for 136 yards, but 75 of those came in the final quarter.

Mendenhall said he was "very surprised" that his team wasn't able to be more successful running the ball against the Aggies.

"Give New Mexico State credit," he said. "Surprised and disappointed. I really thought it would look more like it did at the end of the game. That's what I had anticipated."

With the regular season over, Mendenhall said he will hold a team meeting Monday. The Cougars will lift and run for about two weeks before starting bowl practices. BYU will play a Mountain West Conference opponent, likely San Diego State.

"It will be a fun game," Falslev said. "It will be warm. It's always nice to finish off with two really great weather games with this one and in San Diego. We're looking forward to it."