How much does Urlacher have left? (US Presswire)

A quarter of the way through the season, an anomaly isn’t necessarily an anomaly anymore. It’s a trend. That’s why today in Top Ten with a Twist we’re looking at some of the formerly high-impact players who might be on the down side of their careers. It could be a linebacker who no longer has the speed to go from one side of the field to the other. It could be an offensive lineman who continually gets beat for the first time in his career. It might be a running back whose peak season never has been duplicated.

Four games of so-so production isn’t necessarily a death sentence. But it might give us some insight into how much is left in that person’s career. And it might let us know how much time we have left to see them on the field.

I, however, maintain the right to be proven wrong. Four games might be a trend, but it’s not an entire season. This list isn’t yet definitive. There are still plenty of question marks.

10. Mario Williams, Bills: The $100 million man has been a major disappointment in Buffalo. Through four games, Williams has accumulated nine tackles and 1.5 sacks. That’s probably not what the Bills front office expected when it made the team’s biggest free-agent splash in recent memory. Listen, Williams hasn’t played like a No. 1 overall pick in his short time with the Bills. And he’s only 27. But yes, this season so far is a cause for concern.

9. Randy Moss, 49ers: The fact that Moss is the fourth-leading receiver on his team shouldn’t be a surprise. He missed all of last season, so, at best, he was going to be rusty. But before the season started, he also talked about how sitting out 2011 would make his legs fresher. At 35 years old, that would be an interesting accomplishment if true. Either way, Moss (eight catches, 88 yards) hasn’t become the deep threat Alex Smith would have wanted.

8. Peyton Hillis, Chiefs: The question with Hillis is whether he was an elite running back in the first place. He had a fantastic 2010 season in Cleveland, rushing for 1,177 yards and 11 touchdowns, but since then he’s gained a total of 680 total yards and scored three touchdowns. True, he was injured for part of last season, but with Jamaal Charles taking off in Kansas City, Hillis, at the age of 26, is nothing but a backup at this point.

7. Fred Jackson, Bills: The fact Jackson is 31 and is still viable as a running back in the NFL is impressive. He’s still got plenty of skills, and he still could impact his team in a very significant way, particularly if C.J. Spiller misses a game or two. But the problem with Jackson’s age is that he’s having a tough time staying healthy. He missed six games last year, and in 2012 he injured his knee in Week 1 and didn’t return until last week (where he gained 29 yards on 13 carries). I’m an admirer of Jackson, but I wonder if he’s too brittle to be a 16-game-a-year running back.

6. Tamba Hali, Chiefs: Talk about a guy falling off the map. In 2010 and 2011, Hali combined for 27 sacks and eight forced fumbles, but so far this season he’s recorded one sack and no forced fumbles. He missed the first game of the season because of a suspension for violating the league’s substance abuse policy, and the 28-year-old simply hasn’t played as well as we’re accustomed to seeing. Is he through? Probably not. But should you be concerned? Quite possibly.

5. Antonio Gates, Chargers: We can give Gates a break since he missed part of last season with a foot injury (though he was tough to play through the plantar fasciitis for much of the year), but he’s only got 10 catches for 124 yards in 2012. He’s missed nine games in the past two years, and at the age of 32, you have to wonder if he can rebound. When talking about the best tight ends of the game, is Gates even in the conversation at this point?

4. Ray Lewis, Ravens: The 37-year-old is a fascinating case study for how much age has affected his performance and reputation. Some TV analysts continue to praise Lewis, even when he’s nowhere near the end of a play, and some (like at least one CBSSports.com writer) believe Lewis simply isn’t that good any more. Lewis has accumulated double-digit tackle totals in two of the team’s four games this year, so he’s still productive. And there’s no question that his leadership skills and his pep talks are immensely important to the team. He’s still viable, but you can see the old age beginning to show.

3. Ronde Barber, Buccaneers: The fact Barber is still playing six seasons after his twin brother, Tiki Barber, retired (and a year after Tiki’s failed comeback attempt) is remarkable. But he’s 37 years old, and though he’s a five-time Pro Bowl cornerback, he’s been relegated to the free safety position on the worst pass defense in the league. Not because he isn’t a legit NFL player, but because he showed last season that, at this point in his career, he has a tough time in coverage. Next year, he might have a tough time keeping his job.

2. Jeff Saturday, Packers: After spending his entire 13-year career with the Colts, Saturday signed with Green Bay in the offseason to replace a very good departing center in Scott Wells. So far, Saturday has played like he’s a 37-year-old, 13-year offensive lineman veteran. A top-five center in the Pro Football Focus rankings the past two years, Saturday has slipped to No. 27 in 2012.

1. Brian Urlacher, Bears: It’d be hard to argue that Urlacher has played as effectively as he’s been throughout his 13-year career. He’s coming off a knee injury that kept him out all preseason, so that could be an excuse for why Urlacher is averaging only 4.5 tackles per game. Plus, Urlacher has played so well for so long, maybe we should cut him some slack. But he’s 34 years old and he’s looked slow this year. Are we getting close to the end of what should be a Hall of Fame career?

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