KEY WEST -- In the 13 games played last weekend, only four were decided by 10 or fewer points. The average margin of victory in the other nine was 26 points. Six teams were held to single-digit scores, including the goose egg posted by Oakland.

The disparity between the NFL's best and worst teams is getting more pronounced by the week. And it's killing the fantasy value not just of selected players, but entire teams.

After all, why own a player from a team that rarely scores?

As we head to the halfway point of the fantasy season, the free agent pool is getting shallower, and trading has become the preferred method for improving rosters.

When evaluating trade propositions, don't waste your time if you can't acquire talent from the high-scoring offenses. You're much better off waiting for a Matt Forte or Marion Barber to kick into gear than hoping Justin Fargas or Jamal Lewis posts his team's only points each week.

A look at free agents worth considering, and two who'd look better in someone else's lineup:

CATCH 'EM WHILE YOU CAN

• Shonn Greene, RB, Jets. Though Thomas Jones will remain the lead back, the rookie will play a strong supporting role now that Leon Washington is out for the season.

• Beanie Wells, RB, Cardinals. The rookie made his long-overdue splash Sunday night.

DON'T BE FOOLED

• Jamaal Charles, RB, Chiefs. Larry Johnson has likely played his last game in K.C. (if not the NFL). In keeping with the theme of this week's column, his backup is only worth a pickup for the most desperate of fantasy squads.

• Willie Parker, RB, Steelers. After a game in which he saw only one carry, his value is now solely as insurance for Rashard Mendenhall.

My non-obvious picks to roll, and get rolled, in Week 8:

WATCH 'EM ROLL

• David Garrard, QB, Jaguars. He lit up Tennessee for 323 yards and three TDs in their first meeting, and he has had an extra week to plan his next assault on the league's worst pass defense.

• LeSean McCoy, RB, Eagles. With Brian Westbrook (concussion) out, the multi-purpose rookie is good for at least one TD and 100 combined yards.

• Kevin Smith, RB, Lions. He'll be Detroit's only reliable weapon (assuming Calvin Johnson sits out again) against one of the NFL's sorriest defenses.

• Austin Collie, WR, Colts. He has four TDs over the past three games, and Reggie Wayne(groin) may be limited.

• Terrell Owens, WR, Bills. Ryan Fitzpatrick has connected with Lee Evans for TDs in consecutive wins, and should spread the love to the slumping diva this week in a shootout.

ROLL 'EM BACK

• Joe Flacco, QB, Ravens. He's not likely to excel against a defense allowing 11 points per game and coming off a bye.

• Ryan Grant, RB, Packers. Following his best performance of the season, Grant faces one of the league's stingiest run defenses in what should be a pass-happy affair.

• Knowshon Moreno, RB, Broncos. Sharing carries against a stout Ravens defense is not what you want from your starting tailback.

• Roy Williams, WR, Cowboys. Playing in the ever-widening shadow of Miles Austin, Williams cannot be trusted in your lineup until he and Tony Romo exhibit some chemistry.

• Vernon Davis, TE, 49ers. After his three-TD extravaganza against the Texans, it would be difficult to sit him. But no team has shut down opposing tight ends better than the Colts.

Ladd Biro is a syndicated fantasy football columnist.