CHARLOTTE, N.C. -- There is optimism Cam Newton will be ready for the opener against the Los Angeles Rams after suffering a mild mid-foot sprain in Thursday's preseason loss to the New England Patriots. That was the good news for the Carolina Panthers, but there's still reason to be concerned about the quarterbacks.

Backups Kyle Allen and Will Grier have yet to prove they’re capable of playing at a consistent level should Newton miss time.

Allen, undrafted out of Houston last season, has completed 50% of his preseason attempts in Norv Turner’s offense, which is designed to be heavy on high-percentage passes. He has 124 yards and no touchdowns.

Grier, a Charlotte native and a third-round pick out of West Virginia in April, hasn't been much better at 53.5% for 196 yards and one touchdown with two interceptions.

Between them, they have one NFL start: Allen in last season’s finale, when the playoff-bound New Orleans Saints rested most of their starters. Allen and Grier also have two of the four lowest yards per attempt of any quarterbacks during the preseason, according to ESPN Stats & Information. Allen is averaging 4.4 yards per attempt and Grier 4.6.

The loss to the Patriots magnified how inefficient Allen and Grier -- and the offense in general -- have been during three preseason games. The Panthers had only two first downs and 29 total yards in the first half, and finished with seven first downs and 99 total yards.

They’re averaging 13.3 points and 208.7 yards in three games.

That’s not a recipe for success.

“I was looking for a little more consistency out of the two of them,” said Panthers coach Ron Rivera, continuing a theme throughout the exhibition season. “You know, I thought Will got a little something going at one point, but then we shoot ourselves in the foot with the holding call and then illegal procedure.

“And you can’t expect to have success when you do silly things like that.”

The struggles of the offensive line complicate matters. This rebuilt group, led by free-agent center Matt Paradis replacing retired-and-then-unretired Ryan Kalil (now with the Jets), has several veterans.

Yet so far they haven’t developed the chemistry to allow any of the quarterbacks to work efficiently. Newton was sacked twice in three series, the second resulting in the injury, and had to throw away another pass while scrambling to avoid a sack.

The coaching staff can work on correcting mistakes, but getting Allen or Grier to perform at a high enough level to win -- should Newton’s ankle force him to miss the opener or any other game -- is another story.

An argument can be made that it’s time to bring in a veteran, but there aren't a lot of great options.

Sticking with Allen and Grier would be risky for a team with high hopes of reaching the playoffs. Allen was only ahead in the battle, as Rivera has noted often, because he is “aloof to pressure.” He also was ahead because Grier has been inconsistent in practice and games, as rookies often are.

There are those who in hindsight will argue Rivera should have sat Newton against New England, as he did the first two preseason games, to avoid any uncertainty for the opener. But Rivera and his staff wanted to see how Newton would respond in a live-game situation after missing the final two games last season with a shoulder injury and not throwing during much of the offseason following January shoulder surgery.

While he didn’t throw anything deep against the Patriots to test the shoulder, which has appeared to be fine throughout training camp, Newton was 4-for-6 for 30 yards before the injury. Had he and Christian McCaffrey connected on a screen pass that appeared well set up, his numbers would have looked better.

Newton’s biggest mistake was holding on to the ball too long on the second sack -- the play on which he was injured -- while trying to make something happen.

“You know, it can happen on Game 1 in the regular season,” said Rivera, defending his decision to play Newton. “So, to sit here and say that, well you know, if you don’t play these games, then you play Game 1 and he gets hurt in Game 1. Then what do you do? That’s the hard part; that’s the unfortunate part.”

Tight end Greg Olsen agreed.

“Preseason’s tough,” he said. “It’s the balance of getting some live action that you don’t quite get. We do everything in practice right up until the last minute, right? You don’t get sacked, you don’t get tackled, you don’t get hit in the open field, but you do everything up to that, so you’d like for the third preseason game to get those reps, find some rhythm, find some tempo to what you’re doing and get out healthy.

“Those are kind of the order of the goals. We didn’t get any of those goals accomplished tonight.”

Worse, the Panthers showed they don’t appear to have a backup quarterback capable of leading them should Newton’s next injury be more serious.

“In this league, you can’t just all of a sudden turn a switch and say, 'Oh, we’re gonna be good now,'" Olsen said. “There’s a process about being good and I think we gotta be better at that.

“Obviously, Cam, hopefully he’s OK."