One of the best things about a chat session is the way it can stimulate the imagination. I conducted one a couple of weeks back and I left the one-hour session feeling quite impressed with some of the questions that participants offered. In fact, one inquiry was so interesting -- I was asked to name the player I thought was most critical to his team's success -- that I've decided to turn it into an entire column. The potential of this idea was only reinforced by the overwhelming response to the topic when my colleague, Matt Mosley, presented it on his daily blog earlier this week.
Finally, I'll give you some examples of people who don't qualify. Philadelphia quarterback Donovan McNabb can't be included because Jeff Garcia led the Eagles to the playoffs last season after McNabb sustained a season-ending knee injury. San Diego outside linebacker Shawne Merriman is out as well. He missed four games with a suspension for using a banned substance and the Chargers kept rolling right along. I also can't make a case for Ravens middle linebacker Ray Lewis. Baltimore just has too much talent on its defense.
It's not to say these players aren't valuable. It's just that there are other players whose absences would cause more harm, including:
Kansas City Chiefs
1. Larry Johnson, RB, Kansas City: The Chiefs wouldn't win three games if Johnson wasn't available this season. He set an NFL record with 416 carries in 2006 and their offense seems to deteriorate a little more with each passing season. Right now, Kansas City likely will have a first-time starter at quarterback (second-year veteran Brodie Croyle), a depleted offensive line that lost its two best players over the past two years (offensive tackle Willie Roaf and guard Will Shields) and a corps of wide receivers that ranks near the bottom of the NFL. In other words, the Chiefs had better give Johnson the new contract he covets if they want to have any optimism about their offense this coming season.
2. Tom Brady, QB, New England: Brady produced his most impressive individual season in 2006 -- and that's primarily because he didn't have one wide receiver on his offense that he really trusted. But that's not what makes Brady so essential. There are actually two bigger reasons. First, his presence is vital to the Patriots' hopes of getting the most out of new wide receiver Randy Moss. Second, his backup, Matt Cassel, has thrown 32 passes in the NFL. That's one less than Cassell threw during his college career at USC, where he backed up Carson Palmer.
3. Peyton Manning, QB, Indianapolis: The Colts built their entire offense around this Pro Bowler and he finally helped them win a Super Bowl. They trust him with reading defenses, calling blocking schemes and making the best possible decisions on each down. He's done it for so long -- and at such a high level -- that it's impossible to imagine anybody else doing the job. Especially if it's Manning's backup, Jim Sorgi.
4. Brian Urlacher, MLB, Chicago: As dominant as the Bears' defense has been over the past two seasons, there is no way it would be as threatening without Urlacher in the middle. The Bears lost Pro Bowl defensive tackle Tommie Harris and Pro Bowl safety Mike Brown last season, and Urlacher compensated for those losses with his smarts and athleticism. Just think about what the Bears ask Urlacher to do in their defense. He has to run with tight ends down the middle of the field on passing downs and still be able to attack the line of scrimmage on running plays. How many 6-foot-4, 260-pound linebackers can do that? It says here that the Bears don't want to learn the answer to that.
San Diego Chargers
5. Antonio Gates, TE, San Diego: If the Chargers lost Pro Bowl running back LaDainian Tomlinson, they'd still have the speedy Michael Turner in reserve. If they lost Gates, the best tight end in the NFL, they'd be turning to Brandon Manumaleuna. The reality with Gates is that he's the best receiving option on a team that lacks a true No. 1 wideout. He routinely draws double-teams that make life easier for Tomlinson, quarterback Philip Rivers and any player who's hoping to catch a pass in that offense.
6. Julius Peppers, DE, Carolina: I almost made a case for another Panther -- Pro Bowl wide receiver Steve Smith -- but Peppers is just too vital. There isn't a better athlete playing defensive end in the NFL and he's also the key player on a Carolina defense that has started to decline. Neither defensive end Mike Rucker nor defensive tackle Kris Jenkins is making the same impact he supplied during this team's Super Bowl run in 2003, and they both need Peppers to draw the double-teams he constantly requires from opponents.
7. Michael Vick, QB, Atlanta: Vick wouldn't be on this list if the Falcons hadn't traded his former backup, Matt Schaub, to the Houston Texans this offseason. Now that Joey Harrington and D.J. Shockley are competing to be the team's second-string quarterback, I don't see how new head coach Bobby Petrino can't be frightened every time Vick starts scrambling. Vick may need to prove how much he's grown as a quarterback this season, but that still doesn't change the fact that this team will have a hard time making any plays on offense with him on the sidelines.
8. Walter Jones, LT, Seattle: First, Jones is the best offensive tackle in the game. Second, he's the sole remaining star on an aging offensive line that lost Pro Bowl guard Steve Hutchinson to Minnesota before the 2006 season. Without Jones, quarterback Matt Hasselbeck would be in constant peril and running back Shaun Alexander wouldn't have nearly as many yards on his résumé.
9. Champ Bailey, CB, Denver: The term shut-down cornerback gets used way too often in today's NFL, but Bailey is one of the few players who has earned the right to carry that label. In a league in which defensive backs are hamstrung by rules restricting contact with receivers, Bailey can shadow the game's best wideouts and intimidate the most confident of quarterbacks. He rarely gets all the credit he deserves simply because most teams avoid dealing with him.
10. Carson Palmer, QB, Cincinnati: All you have to know about Palmer is that his presence helped the Bengals become playoff contenders. He's just a notch below Brady and Manning on the short list of elite quarterbacks, and he's going to be even more dangerous now that he's nearly two years removed from the devastating knee injury he sustained in the 2005 playoffs. Bottom line: He's the undisputed leader of a young team that still has a lot of growing up to do.
Jeffri Chadiha is a senior writer for ESPN.com.