Nevada's Stefphon Jefferson is the nation's leading rusher at 175 yards per game. (US Presswire)

With most schools having played four games now, we are roughly a third of the way through the 2012 regular season. There's been a lot of surprises so far. This week's Tuesday Top 10 list: the most pleasant surprises thus far in the college football season.

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1. Oregon State: The Beavers may have had less action than everyone else, but few have proven more in 2012. (Their opener against Nicholls State was postponed.) Mike Riley came into the season on the hot seat, after going 8-16 the previous two seasons. Many in the media projected OSU for last in the Pac-12 North. Riley’s team really struggled with injuries and inexperience at some key spots last fall, but now the Beavers look like a legit Top 20 team. More importantly, by what they’ve done on the field so far, they have proven that they are. Two games in and they already have two wins over ranked opponents (over No. 13 Wisconsin and at No. 19 UCLA .) They've also ruined Heisman candidacies of both Montee Ball and Johnathan Franklin. The Beavers rank No. 2 in the nation in run defense, while young Sean Mannion has emerged as one of the country's better QBs. 

2. The Sun Belt Conference: For years, it's been known as the worst of the FBS conferences. This month, though, it has really taken a big step forward. The biggest statement came when Louisiana-Monroe , led by QB Kolton Browning, shocked No. 8 Arkansas , a 30-point favorite. ULM has since put big scares into Auburn and Baylor to keep the nation's attention. Meanwhile, Western Kentucky , fresh off a 42-17 demolition of defending Conference USA champ Southern Miss , is 3-1. That win improved the Sun Belt to 4-1 head-to-head against C-USA. Oh, and ULM seems set to give the SBC another win over a C-USA program when it visits Tulane this weekend. 

3. Stefphon Jefferson, Nevada, RB: The nation’s leading rusher at 175 rushing yards per game, already has -- in four games -- 270 more rushing yards than he had in all of 2011. The big reason for his improvement apparently is the junior has learned not to get down on himself when some adversity hits. The son of George Jefferson has, um, really moved up on in the ranks of the country's better running backs.

4. Notre Dame: Brian Kelly’s D has been even better than anyone in South Bend could’ve hoped, especially as injuries have mounted in the secondary. Better still, despite starting a redshirt freshman QB, the Irish are No. 5 in the nation in turnover margin. This time last year, they were No. 118. Suddenly, with both Oklahoma and USC losing, the schedule also doesn't seem quite so daunting. BCS bowl? Maybe so.

5. Kansas State: Simply put, Bill Snyder is one of the greatest college coaches in the game’s history. Still, last year his team won an incredible number of close games. It's so hard to come off that and have similar success. His program also lost most of its O-line and three of its top four tacklers from 2011. So K-State had to take a little step back from last year’s 10 wins, right? Guess not. The 'Cats are 4-0. They destroyed Miami two weeks ago, and last Saturday became the first ranked team to beat Oklahoma in Norman in 15 tries.

6. David Ash, Texas, QB: As with everyone else on this list, it’s still early and we need to see how these guys hold up as schedules stiffen, but you have to be impressed by the sophomore’s growth. Ash, who threw eight INTs in his first 150 college throws, has thrown zero in his last 96 attempts. His completion percentage also has increased from 56 percent to 76.

7. Florida: The Gators had a tricky opening month for a young team that's led by a sophomore QB (Jeff Driskel). Already Florida's had back-to-back road tests in very hostile territory -- at Texas A&M and then at Tennessee . Driskel has responded well, throwing just one INT while completing 70 percent of his passes.

8. Mark Weisman, Iowa, RB: Lord knows the Hawkeyes have had their share of bad luck when it comes to tailbacks of late, but the emergence of 235-pound Air Force transfer Weisman, a walk-on, has been a revelation. This weight-room powerhouse sounds like the Big Ten’s answer to Owen Schmitt. Weisman leads Big Ten RBs in yards per carry at 6.4 and is on pace to eclipse the 1,000-yard mark despite not really getting any carries in the first two weeks of the season. He's almost outrushed Montee Ball on close to half as many carries.

9. Rutgers: First-time head coach Kyle Flood didn’t have an easy debut month with three road trips, including one to SEC country to face Arkansas. No problem -- the Scarlet Knights are a perfect 4-0, thanks in large part to the nation’s No. 7 run defense.

10. Morgan Breslin, USC, DE: A junior college transfer, Breslin had some inside the Trojan program wondering if he'd be more than just a guy providing depth for a unit with some big question marks. Was he too stiff? Doesn't look like it now. Breslin leads the nation with 9.5 TFLs to go with five sacks as the extremely young USC D-line has piled up 14 of the team’s 15 sacks.