SNAP SHOT

In one cover-your-eyes snap, the NFL has lost for the season one of its biggest stars, and the AFC has become the great wide open.

New England quarterback Tom Brady, the league’s reigning most valuable player, is done for the year, his left knee shredded when a Kansas City safety rolled into him in the first quarter of Sunday’s opener.

The Patriots put him on injured reserve Monday, entrusting the quarterback job to backup Matt Cassel, who hasn’t started a game at the position since high school.

“You hate to see anyone go down,” Coach Bill Belichick said. “Nobody has worked harder and done more for this team than Tom has. So it’s a tough setback for him.”

Likewise, it’s a huge letdown for the Patriots, who have won three Super Bowls with Brady at the helm. Without Brady as his quarterback, Belichick’s NFL coaching record is 42-58.

Suddenly, the conference is completely up for grabs. Judging by the way teams looked on opening weekend, there’s no clear favorite that is the team to beat.

San Diego lost at home to Carolina. Indianapolis christened its new stadium by losing to Chicago. Cleveland, which has five prime-time games this season, was throttled at home by Dallas. Jacksonville was shut down by Tennessee.

Meanwhile, Tennessee’s Vince Young suffered a knee sprain -- one that reportedly could sideline him for as long as a month -- yet the Titans played better with Kerry Collins at quarterback. And in Pittsburgh, the Steelers rolled over Houston, getting 138 yards rushing from Willie Parker.

The Chargers’ loss had a familiar feel. They lost three of their first four games last season, remember, before regrouping and making a late-season run that carried them all the way to the AFC championship game. They lost to the then-perfect Patriots in Foxborough, falling to New England for the third time in two years.

The budding rivalry between the Patriots and Chargers, although lopsided, was rounding into one of the more compelling matchups in football. With Brady out, the teams’ Oct. 12 rematch in San Diego loses a lot of its luster.

Other observations from Week 1:

* The Steelers, coming off a season in which they made a league-low 11 interceptions, can take hope in the fact they made two Sunday. Better yet, one was by safety Troy Polamalu, who hadn’t picked off a pass in two years.

* With the 1-0 Steelers heading to 0-1 Cleveland on Sunday, it’s worth remembering that Pittsburgh Coach Mike Tomlin agreed with reporters who called the Browns the favorites in the AFC North. He should have thanked them.

* How good is Tennessee’s defense? Good enough to limit Jacksonville’s trampling tandem of Fred Taylor and Maurice Jones-Drew to 31 yards in 14 carries.

* Reggie Bush suffered a partially torn posterior cruciate ligament in his knee last season and decided to stick around New Orleans for an off-season conditioning program rather than coming home to Southern California. It will be interesting to see if that works out for him and the Saints. So far, so good: He accounted for a combined 163 yards rushing and receiving against the Buccaneers.

* Atlanta quarterback Matt Ryan, making his NFL debut, got tons of praise for his performance in a 34-21 drubbing of Detroit, and justifiably so. But don’t overlook what rookie left tackle Sam Baker did. The first-round pick from USC not only did a good job of protecting the passer, but helped pave the way for Michael Turner’s 220-yard rushing day.

It will really mean something if the Falcons can do the same thing to Tampa Bay’s defense Sunday. The Lions are awful.

--

sam.farmer@latimes.com