This time last year there was concern the 49ers' usually-stout defense was taking steps in the wrong direction.
That thought showed itself a few different times down the stretch of the season, including games in New England, Seattle, Atlanta, and later New Orleans in the Super Bowl. The team was top-heavy in talent without much to work with beneath the 11 or 12 players that saw the majority of the time on the field. It cost them when they lost to the Ravens 34-31 and failed to come away with the franchise's sixth championship.
But things have changed this time around. And it looks like those changes are for the better. If Sunday's win over A-level Aaron Rodgers was any indication, this 49ers defense is in far better shape than the one featured during last season's Super Bowl run. There are a few reasons why.
To start, the overall health of two of the team's most important players on the defensive front is drastically improved. Justin Smith is far removed from his torn triceps muscle he played with for the last four games of the season. To his right, Aldon Smith is back as well. His torn labrum he played played the entire postseason with is healed while his body has benefited from his five-week football hiatus taken earlier in the year.
Aldon Smith had one of his best performances of the season Sunday in Green Bay, getting to Rodgers with two sacks, two hurries and a hit. Unlike last season, he's found ways to get to the quarterback consistently without relying on Justin Smith as often in two-man stunts.
"He's back in football mode," Ahmad Brooks said about Aldon. "It's good to see him out there working, working hard and just doing what he usually does - being Aldon Smith, being the great pass rusher that he is."
Brooks' play in 2013 earned him second-team All-Pro honors for the second-straight season, while his sack numbers jumped from eight to 11.
Defensive coordinator Vic Fangio said Brooks spent the offseason working to improve his game as a pass rusher.
"Learned through what works, what doesn't work, what's best for him, what's not best for him. And just having more opportunities," said Fangio.
The added depth at outside linebacker behind Smith and Brooks has paid dividends, unlike last year. Dan Skuta and Corey Lemonier filled in during Smith's absence and played well enough to help the team win all five games he missed.
Last year, Clark Hagans was the 49ers' only reserve outside linebacker, forcing Brooks and Smith to play nearly every play. Skuta and Lemonier have given defensive coordinator Vic Fangio the ability to rotate and keep the miles down. And that hasn't been limited to linebackers. The defensive line has also benefited.
"I don't know if fresh is the right word, but healthier," Fangio said prior to the team's game in Green Bay.
The play of Tony Jerod-Eddie and Demarcus Dobbs has allowed Ray McDonald and Justin Smith to take drastically fewer reps. Through 17 games in 2012, McDonald and Smith took 1037 and 1018 snaps respectively. This season they have taken 710 and 843.
The secondary has taken a different shape. Rookie Eric Reid stepped in for former All-Pro and went the entire season without committing a penalty. Now with Tampa Bay, Goldson's been fined numerous times and even suspended for two games (his appeal dropped one to a $100,000 fine) so far in 2013.
But even in his rookie season, Reid's been the better player while making $7 million less against the cap.
"He's a very smart guy, very mature," Fangio said of his new safety. "He's emotionally stable. Very coachable and the game's not too big for him."
Against the Panthers Sunday, the 49ers face a unique test in stopping Cam Newton and their physical yet versatile running game. The only team that's posed San Francisco with a similar attack is the Seahawks, who are the only team in the NFL the 49ers have lost to in each of the last two seasons.
Even with the influx of new players taking snaps from many of the stalwarts, the overall production of the defense has been stagnant. The team finished third in scoring in each of the last two seasons and dropped its average allowed from 18.2 per game last year to 17.2.
*Statistics from Pro Football Focus were used in this report*
Follow Editor in Chief Chris Biderman on Twitter.