Different defensive schemes. Offensive line problems. Issues in the running game. Pressing. A sophomore slump.

Whatever the reasons, Carolina Panthers quarterback Cam Newton is well off the pace he set in his record-breaking rookie season.

An Observer review compared Newton’s performance against the Broncos to his best passing game (according to passer rating) of the season, against New Orleans in Week 2. It showed he had less time to make completed passes, reflecting an offensive line that allowed seven sacks and the Panthers’ weak rushing game.

The review showed:

• Against New Orleans, Newton registered his highest single-game passer rating of the 2012 season at 129.2. He went 14-for-20 with 253 yards and one touchdown. He was sacked once, on a four-man rush. (The Saints defense, currently ranked last in the league, was in just its second game under a new defensive coordinator.)

Against Denver on Sunday, Newton’s passer rating was 74.0, just above his season average. He went 21-of-36 for 241 yards, two touchdowns and two interceptions, and was sacked a career-high seven times. (Denver’s defense, currently ranked sixth in the league, features the NFL’s top sack duo, linebacker Von Miller and defensive end Elvis Dumervil.)

Last season, Newton averaged an 84.5 passer rating.

• Newton took more time to throw the ball versus the Saints – releasing the ball in an average of 2.6 seconds per completion. In that game, he had a healthy offensive line to offer protection and an effective running attack that gained 219 yards on 41 carries.

Against the Broncos, Newton’s completions were released two-tenths of a second quicker – in an average of 2.4 seconds. The offensive line struggled and the Panthers gained only 52 yards on 21 carries, and Newton was rushed by a blitzing defense that sacked him seven times.

• Against the Saints, on passing plays that took 3.0 seconds or more to develop, Newton went 5-for-6 for 132 yards and took his lone sack, which came on a four-man rush.

On passing plays that took 3.0 seconds or more to develop against Denver, Newton was 4-for-7 for 24 yards, threw a touchdown pass and an interception and was sacked five times.

Much changed for the Panthers between Week 2 and Week 10 – the coaching staff has all but abandoned the zone-read rushing scheme to go to a more traditional, power style, and the offensive line has been shuffled after Pro Bowl center Ryan Kalil went down for the season with a foot injury.

Sunday, against the Broncos, the problems coalesced. A breakdown of the issues:

Blitz pickup issues

On the eight plays when the Saints blitzed in Week 2, Newton went 5-for-8 for 94 yards and a touchdown against the Saints while taking 2.8 seconds per snap. He was not sacked on a blitz.

The Broncos blitzed 11 times, and Newton went 6-for-8 for 75 yards and two touchdowns (short passes to tight end Greg Olsen) on those plays. But he had only 2.6 seconds per snap and was sacked three times.

“The hardest thing that happened for us as far as the offense was protection issues,” head coach Ron Rivera said. “Our young guard (rookie Amini Silatolu) was exposed. Actually, both of our guards (Silatolu and Jeff Byers) were exposed. That’s something we have to make sure we shore up and not allow that to happen. We saw when Cam has the time to throw the ball downfield, he can. We just have to make sure we protect.”

Sacks, knockdowns

The Broncos hit Newton five times as he threw, and all those passes went incomplete with the exception of an interception returned for a touchdown. Of Denver’s seven sacks, one came on a Newton scramble, two on missed assignments (one by the tight end, one by the fullback) and four on missed blocks by offensive linemen.

“The toughest thing for a quarterback is if he’s getting hit, why is he getting hit?” Rivera said. “Do you lose confidence in (whether you) are you being protected or not? You lose confidence in your decision-making.”

Few audibles

Unlike quarterbacks such as Denver’s Peyton Manning or New Orleans’ Drew Brees, Newton doesn’t have much freedom to audible at the line of scrimmage if he reads a blitz. Rivera said the team has double calls in the huddle, but few changes of the play call at the line.

“It’s not necessarily limiting what he can do at the line of scrimmage,” offensive coordinator Rob Chudzinski said. “Some of the things you want to get in rhythm as an offense and are just ‘go’ plays, and you’re going to run them no matter what you see. There’s other things where he does need to check and has the ability to check.

“There are different style offenses. Some people go up there and check every single play. That’s not what we’re doing right now.

“I don’t see doing that anytime soon.”

Sophomore slump

With seven games left in the season, Newton is on pace to finish with 3,810 passing yards, a 57.2 completion percentage, 14 touchdowns and 18 interceptions.

As a rookie a season ago, Newton completed 60 percent of his passes for 4,051 yards, 21 touchdowns and 17 interceptions. He was named the NFL’s Offensive Rookie of the Year.

Sophomore slump?

“I could jump on it and use it as an excuse but I’m not going to,” Rivera said of the sophomore slump. “He’s trying the best he can and we’re trying to help him as much as we can.”

Rivera said this week he would continue to evaluate his offensive line, leaving open the possibility of changes. He made one this week, bringing back a former Panther, offensive guard Jeremy Bridges, who worked with the first team in Wednesday’s practice.

Rivera says his team must protect Newton better, run the ball more effectively and make fewer mistakes.

“It comes back to execution and not just him,” Rivera said. “There are 10 other guys that have to do their job as well. It’s a team.”