Somehow, some way, despite playing without seven veteran starters, coordinator Mel Tucker's defense has gotten better.
After being gashed for an average of 29.4 points in the first seven games, the Bears have not allowed more than 21 points in any of the past three games, including victories over Green Bay and Baltimore.
Contact information ( * required )
In those 2 wins, the defense permitted its fewest total yards this season, 312 against the Packers and 317 vs. the Ravens.
Tucker and his staff have done it with an eclectic mix of players old and new.
The defense is playing without three Pro Bowlers (linebacker Lance Briggs, cornerback Charles Tillman and tackle Henry Melton), in addition to veteran starters D.J. Williams, Nate Collins and Shea McClellin.
In the second quarter Sunday, nose tackle Stephen Paea reinjured the toe that kept him out of two games earlier in the season, and he's week to week.
Fortunately eight-time Pro Bowl end Julius Peppers has re-emerged as an impact player after a disappointing first half of the season.
He had 11 tackles Sunday, almost unheard of for a lineman. Four of his tackles were for negative yardage, including 2 sacks, doubling his season total.
"He's obviously gaining strength and momentum," coach Marc Trestman said. "Really, his energy level was consistent throughout the game. We all had a sense during the week that this was going to be a game that he was going to turn it up. It was good to see."
But Peppers can't do it alone.
Several new and mostly inexperienced players also have stepped up their games. Five who helped defeat the Ravens had never played a single snap in the NFL before this year.
Those five were on the field for a combined 240 snaps Sunday, led by rookie middle linebacker Jon Bostic (all 81 snaps, 5 tackles), first-year nickel cornerback Isaiah Frey (64) and end David Bass (59).
Bass' interception and 24-yard TD run tied the game 10-10 in the second quarter.
"I thought Jonathan had his best game, in terms of his physicality and in terms of running from sideline to sideline," Trestman said.
"Isaiah has just a very mature quality about him. He's a solid guy in terms of assignments, and that's really helped my confidence in the back end, because of his play in the nickel."
Three players who slogged through the mud in Sunday's marathon weren't even with the Bears in training camp: four-year veteran tackle Landon Cohen, who played 60 snaps, Bass and undrafted rookie tackle Christian Tupou (18 snaps).
End Cheta Ozougwu played in two games for the Bears last season but was waived in the final cutdown this year. He was re-signed to the practice squad Sept. 24 and promoted to the 53-man roster a day before the Ravens game.
Although he played just 18 snaps, the 6-foot-2, 255-pound Ozougwu sacked Joe Flacco on a fourth-and-8 from the Bears' 32 midway through the third quarter.
Trestman says he has gained confidence in the defense, even as the injuries have mounted.
"I see the work that's being put in (during practice)," he said. "I see the run fits getting better, the communication getting better.
"I like the fact that our coaches are embracing the development of our young players. We're not spending time thinking about the players we've lost.
"We've taken all that energy into building the best defense we can to play good team football. I'm confident we're doing that weekly.
"So when the game comes and it doesn't go well at some points it doesn't really change my feelings overall of how we're going to call the game offensively or manage the game until more of it evolves."
Briggs remains week to week with a fractured shoulder, but he could be back for the Minnesota Vikings (Dec. 1), as well as tackle Jeremiah Ratliff (groin).
Both still are considered week to week, while end Shea McClellin is expected back at practice this week after missing two games with a hamstring injury.
•Follow Bob's NFL and Bears reports on Twitter @BobLeGere.