Three of the top six AFC teams and two of the top six NFC teams already have made trades ahead of Tuesday's deadline. With more certain to follow and considering last year's activity at the deadline, a once overlooked date on the NFL's calendar is growing into another gold mine of breathless speculation.

Who's going to get Trent Williams? How about A.J. Green? Should the Bears pull the trigger and trade for Marcus Mariota? Should the Vikings, now deep again at corner, see what some of these cornerback-starved teams would pay for Xavier Rhodes? Or should they go after Green and really load things up for Kirk Cousins for this home-run season while keeping the All-Pro Bengals wideout from landing alongside Aaron Rodgers in Green Bay?

The Bengals say they aren't shopping Green. But they're winless. Green isn't likely to sign a long-term deal when his contract is up after this season. He's probably tired of playing with Andy Dalton. And, besides, teams always say they aren't shopping a player until they do (see: Harvin, Percy).

The Vikings shouldn't mortgage their future. But it would be OK — even encouraged — to be open to overpaying a bit for an immediate impact player with the understanding that A, their defense is built to win now; B, they don't know how many years Dalvin Cook will be this healthy and this ridiculously explosive, and C, it's best to strike while Cousins is hot because he tends to go cold just as quickly.

Last year's trade deadline saw some big moves that relocated the likes of Amari Cooper, Golden Tate, Ha Ha Clinton-Dix, Dante Fowler Jr. and Demaryius Thomas. But this year has been topping last year for some time now.

The Texans keep making moves without hesitation because the coach, Bill O'Brien, operates as his own general manager. He's traded for Laremy Tunsil, Kenny Stills, Carlos Hyde and Duke Johnson.

He also got a third-round pick for Jadeveon Clowney, but that pick will end up going to the Raiders for cornerback Gareon Conley. O'Brien made that trade last week, a day after Jacoby Brissett threw for 326 yards and four touchdowns while beating the Texans and a secondary that finished the game with one healthy corner.

The Patriots, of course, went from 7-0 and allowing 6.9 points per game to being an even stronger force when Bill Belichick finally got his hands on big Falcons receiver Mohamed Sanu. People say Belichick overpaid with a second-rounder, but how can you blame him for keeping this current title-collecting window open as long as possible?

The Rams made the biggest splash of the season so far by grabbing Jalen Ramsey from Jacksonville. Then they dealt Marcus Peters to the Ravens, who watched as Peters' Baltimore debut earned him the distinction of being the first player in NFL history to record a pick-six for two different teams in the same season.

The 49ers, meanwhile, were playing it cool when pressed about their urgency to add a receiver. But as soon as Sanu went to New England, the 49ers quickly took a chance on an aging, beat-up Emmanuel Sanders while giving Denver picks in the third and fourth rounds next year.

Defensively, the Lions surprised team captain Quandre Diggs this week by shipping him to Seattle, which has been loading up on defenders and still is looking for corners like the Broncos' Chris Harris Jr.

In the AFC, the Chiefs need corners and could be looking to cash in on defensive coordinator Steve Spagnuolo's relationship with Janoris Jenkins when they were together with the Giants. Meanwhile, the Colts and Bills both are looking for receivers such as Green and Philly's Nelson Agholor.

In the NFC, the Saints and Packers also could be looking for receiver help like the ones already mentioned, and possibly Miami's DeVante Parker. The Cowboys might be in the market for defensive-line help.

And in Minnesota, the Vikings like the 6-2 team they've assembled. But the way the NFL trade market has opened up, the Vikings should at least be exploring opportunities to add another impact player, even if it requires overpaying a little bit to keep pace.

Mark Craig is an NFL and Vikings Insider. Twitter: @markcraigNFL E-mail: mcraig@startribune.com