"I've played hard all the time and for some reason it just came together for me today in the second half, and hopefully it will continue," said Brown, the Bears' fourth-round draft pick out of Florida.
Brown made seven tackles, second on the team and four short of leader Lance Briggs. He also had a sack and fumble caused.
Brown got around the corner in the early third quarter and knocked the ball out of Joey Harrington's hand while he attempted to pass on second-and-12 from the Lions' 25 for an 8-yard loss. Lions lineman Eric Beverly recovered. The sack lifted Brown's team-high sack total to 2.5 and matched his rookie total.
"I just reached and there it was," Brown said of the ball. "It was just reaction of what we practice all the time."
The play left the Lions in bad field position and when Phillip Daniels swatted down a Harrington screen pass the next play, the Bears were set up with the ball in good field position at the 50 to drive for the game's only touchdown.
"Alex had a good day today," Bears defensive coordinator Greg Blache said. " I was glad to see that he made some plays and showed up.
"That's what we've been hoping for and we hope that he can continue for the rest of season, take off and go from there."
Brown's bigger contribution may have been in the running game and against the Lions' rollout passing game. Brown's weakness had been the run, but he had a hand in limiting Detroit to 17 rushing yards, the lowest total allowed by the Bears since Jauron has been head coach. One play before his sack, Brown had stuffed Lions running back Shawn Bryson for a loss of 2.
The Lions also tested him with the screen pass, and he responded on plays back across the field.
"If they rolled away from us, then I've got to stay back side because they threw a lot of screens that roll one way and threw back," he said. "On one play I stayed back side and it worked out for us and he threw it in the ground. But if they roll out it's kind of difficult, because you can't run after them knowing they could screen you."
The stats and plays were nice, but Brown came away feeling empty.
"I'd rather win than have sacks or hurries," said Brown.