Dan Pompei

It can be dangerous to assume that NFL players will continue to produce as they have in the past — but we all do it.

For some reasons that are impossible to predict, and others that are easier to foresee, the truth is the performance levels of some players will plummet like cliff divers. Here, then, are some players who could be in for a production dip based on circumstances that are evident as camp kicks off.

Tom Brady, Patriots QB
I would never doubt Brady’s resolve, courage or industriousness, but it isn’t easy to come back quickly from the kind of knee injury he suffered last season. He is fortunate because he does not depend on his legs much from a running standpoint, but his knee could affect his ability to throw and/or avoid pressure, at least in the short term.

Carson Palmer was in a very similar situation in 2006, and he was not completely comfortable with his knee until the ninth game of the season. Donovan McNabb’s return from a similar injury in 2007 also was marked by ups and downs.

Brady still should be very good. But he might not be the game's best passer that he had been, at least in the first half of the season.

Antonio Bryant, Bucs WR
Last season easily was the best of Bryant’s seven-year career. He had 83 catches for 1,248 yards and eight touchdowns after averaging 41.6 catches for 639.5 yards and 3.1 touchdowns in his previous six NFL years. Bryant also had been given up on by three other teams.

It is possible that he has turned the corner in his career and matured as a player and person. But it also possible — maybe even probable — that he will return to form in 2009.

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It may not help Bryant that either Byron Leftwich or rookie Josh Freeman will be throwing to him this year instead of Jeff Garcia. At the very least, he will need to develop chemistry with a new passer.

Aaron Kampman, Packers OLB
What we know is Kampman is a fine defensive end in a 4-3 front. What we have no idea about is how Kampman will play at outside linebacker in Green Bay’s new 3-4.

Many suspected Kampman was not happy about the position switch, but he’s apparently over that now and new coordinator Dom Capers has praised him for his progress.

Capers also says Kampman won’t be dropping into coverage much. But there is little doubt Kampman has a lot to learn and a lot to adjust to.

Eli Manning, Giants QB
In the last two years, Manning has lost these weapons: Plaxico Burress, Amani Toomer, Jeremy Shockey and Derrick Ward. It’s true that quarterbacks are more likely to make the receivers better than the other way around, but sooner or later, this trend could catch up with Mr. Manning.

In particular, Manning could miss a big, physical presence at receiver. He has to hope that someone steps up from a group that includes Domenik Hixon, Mario Manningham, Hakeem Nicks and David Tyree.

Brandon Marshall, Broncos WR

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I’ve liked Kyle Orton going back to his days at Purdue and believe he will do well in Denver. But no one can deny he doesn’t throw the deep ball like Jay Cutler. And one of the things Marshall does best is get vertical and make big plays.

That dimension of his game probably will be diminished with the quarterback change.

Kyle Vanden Bosch, Titans DE
Vanden Bosch had Albert Haynesworth to thank for many of his one-on-one pass rushing opportunities. They often lined up on the same side of the line, forcing offenses to take a chance that Vanden Bosch wouldn’t beat them.

Now that Haynesworth is in Washington, it will be easier for opponents to concentrate more on stopping Vanden Bosch.