Just four weeks in, you can already spot certain rookies that appear to belong in the league and others that seem like they are lost. Some are predictable, others are surprises. Here are several observations.

The big name running backs have both performed. Adrian Peterson and Marshawn Lynch are both for real. The Vikings need to get Peterson on the field more because it's clear he's a superstar already. He runs hard and fast and has already gained 383 yards. Lynch isn't far behind with 307 yards. Both rookie backs appear to be franchise backs at this point. Nobody else is even close, with undrafted Selvin Young third in rookie rushing with 138 yards.

The rookie receiver studs aren't exactly who you expected at this point. Sure, Calvin Johnson has 189 yards in three games (he missed Week 4 with a back injury) and two touchdowns. And we could have predicted Dwayne Bowe would be solid, but not spectacular like he is so far. Bowe has 299 yards and three TDs already. The surprise of the class has been James Jones, a third-round pick from San Jose State that has 232 yards already in the Packers offense and looks like he's played for years. Other top picks have struggled, including Ted Ginn, who the Dolphins don't even put on the field, Robert Meachem and Craig Davis.

We'll have to wait a while to see the rookie quarterbacks. JaMarcus Russell signed very late, which means he probably won't even get on the field this year. Brady Quinn also signed late, but could see the field shortly. The only guys that have even thrown a pass are Trent Edwards and Kevin Kolb, with Edwards starting for the injured J.P. Losman and winning his first start and throwing for 331 yards.

For teams, there's no bigger surprise than the Packers at 4-0. Dallas, New England and Indy are also undefeated, but that's not a shock to anyone. San Diego already losing more games this season than they did all of last season would blow any Vegas odds, while everyone's sleeper, St. Louis, can't seem to find any offense or stop anyone.