But Mendenhall was non-committal when he was asked on Monday if Nelson will start Saturday at Oregon State.
"He'll be the one who will have a chance on Saturday," Mendenhall said. Asked point-blank if Nelson would be the starter, Mendenhall repeated his previous answer: "He'll be the one who will have a chance on Saturday."
Sophomore Jake Heaps, who started the first five games this season, did not play at all against San Jose State.
Mendenhall said that there has been discussion among the coaching staff about getting Heaps back onto the field for a couple of series, but Mendenhall is leery of playing two quarterbacks.
"It gives us a great chance to continue to either develop one, which adds consistency, or train two, which sometimes takes away from consistency, which I learned a year ago," Mendenhall said. "Most likely, the starter, as long as they're playing well, they're going to play probably through the whole game."
Saturday marked Nelson's first start of the season. He completed 14-of-24 passes for 219 yards, with two interceptions and three touchdowns. Nelson rushed for 65 yards on nine carries and he gave up one fumble.
"The type of quarterback Riley is, he buys more time," Mendenhall said. "When under pressure, he's able to elude the rush, which gives the receivers more time to get open, which then makes us more difficult to defend because he can throw it to a receiver whose route has been adjusted. It's harder to cover adjusted routes."
Mendenhall also likes the way Nelson can pick up yards by running the ball, which made the offense "much more difficult to defend. I think that it provided a spark and an inspiration to our team and it gave us some momentum going into a road game."
Meanwhile, Mendenhall said Nelson needs to cut down on turnovers. "The only thing I would fault him on would be ball security," he said.
Wide receiver McKay Jacobson caught two passes for 63 yards, including a 40-yard touchdown, from Nelson.
"Riley has a lot of grit out there. He's just a tough player," Jacobson said. "He does a good job just going out there and playing. In the last game, he made a lot of great plays. Offensively, we did a lot of good things. There's some room for improvement with scoring and taking care of the ball better. But I think he did a good job."
Jacobson acknowledged that the play-calling has been different with Nelson at quarterback. "There's some different things we're trying to do, calling plays that kind of fit Riley's skill set," he said. "Offensively, we've been progressing and executing better and better."
And how is Heaps dealing with his demotion?
"It's tough sometimes when you see a player struggle or not go a particular way for a player," Jacobson said. "But overall, he's been working hard, just like everybody else, and staying focused on the task at hand and putting in the work each day. … I think he's working harder."
INDY PLAYER OF THE WEEK: BYU placekicker Justin Sorensen earned independent special teams player of the week honors.
Sorensen booted a pair of field goals, from 42 and 45 yards, and connected on all three PAT attempts. The sophomore from South Jordan is 9-for-11 on field goals and 13-for-13 on PATs this season.
Notre Dame quarterback Tommy Rees and Fighting Irish safety Jamoris Slaughter were the offensive and defensive independent players of the week, respectively.