A year ago, defensive coordinators envied what the Baltimore Ravens did in stacking the middle of their defense with powerful, run-stopping tackles.

For the first few days in free agency this year, tackle-starved teams should be able to make some big moves. The defensive free agent class is rich at the top in tackles and also offers some of the better middle linebackers available in recent years.

Quick-responding coaches can fill instant needs in the middle of their defensive lines. Want an inside pass-rusher? You can sign La'Roi Glover, who had 50 sacks over the past five years with the Saints. Want run-stuffers? Go for John Parrella of the Chargers or Grady Jackson of the Raiders. Want a combination of both, sign Sam Adams of the Ravens, who was expected to void the remaining two years of his contract.

Defensive end free agents aren't as strong. The Rams don't want their best pass-rusher, Leonard Little, hitting the market, but figuring out where he fits in terms of value isn't easy. The Rams used him as a backup because, at 242 pounds, he's not big enough to be considered an every-down player. Reinard Wilson of the Bengals finally got a chance to move to defensive end from linebacker and rush the quarterback. He had nine sacks, but teams still remember his struggles as a linebacker. Keith McKenzie of the Browns is a great pass-rusher but is coming off an ankle injury.

An interesting name to follow is Kenny Mixon, who is an every-down player for the Dolphins and mixes stopping the run along with skills for rushing the quarterback. Renaldo Wynn is former first-rounder of the Jaguars and will be a hot target.

The best players at linebacker are two who weren't expected to hit the market. Chiefs outside linebacker Donnie Edwards has played about 95 percent of the defensive downs over the past five season, but the Chiefs' desire to keep his salary around $3 million is forcing him to void his contract. Kevin Hardy of the Jaguars is the perfect outside linebacker who can rush and drop into coverage. Middle linebacker Sam Cowart is the Bills' best defender, but the team is reluctant to guarantee multi-millions up front because of his recent Achilles tendon tear.

Those who can't entice Edwards will look closely at Jets wide side linebacker James Farrior, whom the team would like to keep. Losers of the Cowart sweepstakes will study Earl Holmes of the Steelers, London Fletcher of the Rams and Jamie Duncan of the Bucs. But if they can't find big dollars elsewhere, Holmes, Fletcher and Duncan might return to their current teams.

The top cornerbacks mostly come from the 1997 and 1998 drafts, and they are looking for their second NFL contract. Duane Starks of the Ravens is coming off a difficult season. Corey Chavous of the Cardinals is a big cornerback who can fit into a two-deep zone system. Tom Knight of the Cardinals, Artrell Hawkins of the Bengals and Walt Harris of the Bears are former high draft choices looking for new homes.

Safeties usually are casualties in tight cap markets such as this, but there are good ones available -- both young and old. Robert Griffith of the Vikings is perhaps the best available. Good young talents such as Shaun Williams of the Giants, Tony Parrish of the Bears, Lance Schulters of the 49ers and Pat Tillman can fill out any quality secondary.

John Clayton is an ESPN.com senior writer.