Brown gets tested by double duty

FOXBOROUGH -- For the third straight year, receiver Troy Brown has bailed out the Patriots' banged-up defensive backfield by playing cornerback, mostly on third down in the slot. He gains a greater appreciation for the task each season.

"It's tough," the 14-year veteran said. "You have different types of receivers. Big. Strong. Quick. Big and quick. Small and quick. Small and fast. You just never know where they're going or when you're going to get picked on by somebody."

The 35-year-old Brown has fared well the last two weeks as his defensive snaps have increased. He has lined up against Green Bay's Donald Driver and Chicago's Rashied Davis and Muhsin Muhammad, and could be called upon again today if defensive back Chad Scott (groin) is sidelined for the second straight week.

Since making the switch to defense, Brown sees the NFL's rules on pass interference and illegal contact from a different perspective.

"It's a tough spot to be in," he said. "Things happen. You can see it on the replay and it looks easy. When it happens at game [speed], it's a judgment call and you can't review it -- the guy didn't arm-bar him, he didn't touch him before the ball got there, he did look back for the ball -- and it's just tough to make a call on that when you see it in game [speed].

"It's all judgment and they make a decision and you have to live with it. We as players have to keep playing."

Brown, who is third on the team with 30 receptions, has been challenged by the double duty.

"At receiver, you get the call and you know where you're going -- you read the defense and you get to the spot," said Brown. "On defense, you're waiting for someone else to react and you have to react a step faster. And there are so many different things going on, and you have so many different coverages in your head, wondering where your help is coming from."

As part of his annual predraft scouting trip to Florida, Patriots coach Bill Belichick spent "quite a bit of time" with Florida State linebacker Ernie Sims. Belichick came away impressed, but the Lions ended up snatching Sims at No. 9, well before the Patriots picked (21st). Sims enters today's game against the Patriots with a team-high 109 tackles and has several of the qualities the Patriots generally seek. "He's a football guy. Business. Very competitive. Very intense," said Belichick, noting that even though Sims is undersized at 6 feet, 225 pounds, he still could have fit in the middle of a 3-4 defense. "I think football is important to him and he plays like it on the field. Every play he's after you."

Running back Patrick Pass, who opened the season on the physically unable to perform list and returned to action for the first time last week, feels he's fully part of the team again. "It's hard when you're not there to physically endure what everyone is going through," said Pass, who played solely on special teams last week. "When you're not out there, you feel like you're letting the team down. Just getting back was an unbelievable feeling, being out with the guys again." Pass, who has been with the team since being selected in the seventh round of the 2000 draft, said the 10-game stretch he missed was the longest of his career . . . The Patriots re-signed offensive lineman Gene Mruczkowski yesterday, filling the 53d spot on the roster. Mruczkowski, 26, who initially joined the team as a rookie free agent in 2003, has played in 17 games with the Patriots over the last two seasons and adds depth at center and guard.

The last time the Lions visited Foxborough was Sept. 12, 1993, the second game of Bill Parcells's four-year tenure as Patriots coach. The Lions won, 19-16, on a Jason Hanson 38-yard field goal in overtime. Hanson is now in his 15th season with the Lions, which ties him with Green Bay's Brett Favre for the longest tenure any active player has with the same team . . . Former Patriots offensive lineman Damien Woody, who signed with the Lions prior to the 2004 season, was lost for the season with a foot injury after playing in five games . . . The Patriots are 19-5 in the month of December since Belichick became coach in 2000 . . . The Lions are coming off a long week and thus had extra time to prepare after losing to the Dolphins at home on Thanksgiving, 27-10 . . . The Patriots are one of only three teams to rank in the NFL's top 10 in yards gained per game (seventh, 346.9) and yards allowed per game (sixth, 286.8). The other teams are Dallas and San Diego.

Belichick came to the defense of his former defensive coordinator, current Browns coach Romeo Crennel, whose team is 3-8. The Browns went 6-10 last year in Crennel's first season. Belichick said wins and losses are not always representative of the progress a team is making. "I think that's a good example of a team that's a lot better than it was a couple of years ago, from what I can see, in a lot of areas," said Belichick. "It's hard sometimes because we get so swayed by the final score. If we win, everything is great; if we lose, everything is terrible. Well, that's really not the way it is, so it takes some patience, especially if you're not getting the results in the win-loss column that everybody would like to see." . . . Remember the play against Green Bay, when Brady lined up at wide receiver? Reche Caldwell said it's not the first time. Brady has done demonstrations with the receiving corps on how he wants routes run. "It doesn't look as good as the receivers, but it's the correct technique and he always teaches us the right thing," said Caldwell.

Mike Reiss can be reached at mreiss@globe.com; Christopher L. Gasper of the Globe staff contributed to this report.