However, there are strong indications that BYU is preparing for Hill to start. Hill said he received the bulk of the reps on Monday, and Nelson acknowledged he's not close to being healthy.
"Boy, not very high [percentage]," Nelson said. "But I really want to play, and really want to be out there and battle with my guys. Today, it was better than it was Thursday. Thursday, I would say 65 percent. Today, 75, 80 [percent]."
BYU won't officially disclose the nature of the back injury, and Nelson told reporters to ask head athletic trainer Jeff Hurst. But he wasn't made available.
"He's got a sore back. He took a hard hit in the Weber State game," said Mendenhall, who later talked about not wanting to share injury information because it might give opponents a competitive advantage.
Mendenhall said he isn't sure whether Nelson's three interceptions and fumble against Boise State, and his mistakes against Utah, can be attributed to the back pain.
"They are probably attributed somewhat to it. But I don't know what percentage we could assign to it. After the second [mistake], it was clear to me that it was kinda beyond what he could even handle. So that's why we made a change," Mendenhall said.
If Nelson does play Friday, will coaches have him on a shorter leash?
"I think I will have a lot better assessment of what the signs are," Mendenhall said. "And he has a more open line of communication with me now. He kind of knows what the signs are. It is kind of a learning process."
Mendenhall said nobody mentioned his controversial and ill-fated decision to go for the two-point conversion against Boise State from the time he talked to reporters after the game until after Monday's practice.
"I was working the door at the [Brigham City] temple dedication, as a greeter. You would think that would be a great opportunity. But no one mentioned a thing about it. The team hasn't, the coaches haven't, my wife hasn't. My relatives' friends haven't. So you guys are the first," he said.
He reiterated that he would "do it again, in a second, if we played again tomorrow."
Mendenhall said defensive end Ian Dulan is still struggling with a back injury and "might" be out for the season. Running back Adam Hine has a quad injury and will likely be out another week or two. Defensive end Eathyn Manumaleuna, who tore up his knee against Boise State and is out 6-12 weeks, will seek a medical hardship through the NCAA to get his year back.
BYU punter Riley Stephenson, a senior from St. George, is the FBS Independent Special Teams Player of the Week after averaging 47.0 yards per punt on his six punts in the 7-6 loss to Boise State. ... ESPN has added the Nov. 17 BYU-San Jose State game and the Nov. 24 New Mexico State-BYU game to its lineup, and says the games will be shown on either ESPNU or ESPN3. ... BYU confirmed Monday that it has agreed to a home-and-home series with Middle Tennessee State, with the Blue Raiders visiting Provo in 2013 and BYU traveling to Murfeesboro in 2014.
Hawaii at BYU
P Friday, 6 p.m.
TV • ESPN