Connecticut junior Donald Brown leads the nation with 906 rushing yards and is on pace to eclipse 2,000 yards this season. Jim Rinaldi/Icon SMI

By Tony Pauline, Special to SI.com

Four nationally ranked and previously unbeaten teams went down to defeat this weekend in college football, sending tremors through the rankings. Players from several of those winning teams are deservedly watching their draft stock rise, while the situation at quarterback continues to look bleak.

Risers

Andy Levitre/OL/Oregon State: The Beavers offensive line dominated the talented Trojans during their upset victory, and Levitre's play was key. Oregon State's left tackle did an outstanding job protecting his quarterback's blind side and displayed surprising run-blocking strength. NFL scouts project Levitre inside to the guard position and consider him one of the smartest senior blocking prospects available in April's draft.

Victor Butler/DE-LB/Oregon State: Butler was another who came up large in the Beavers' victory over USC, posting five tackles and recovering a fumble. He leads the team in tackles for loss (3) and ranks first amongst defensive lineman in tackles (18). Butler is a terrific athlete but a bit small (6-foot-2, 233) for the defensive end position he plays, yet has the speed to make the transition to outside linebacker.

Antoin Caldwell/C/Alabama: The Tide scored 31 first-half points on their way to demolishing No. 3 Georgia. Alabama's offensive line dominated a talented Bulldog front wall of defense all night and nowhere was this more apparent than in the center of the line. Caldwell opened holes in the middle of the field and was a terror blocking on the move. He rates as the No. 2 center in the nation and will be off the board in Round 2 next April.

Donald Brown/RB/Connecticut: UConn is off to a blistering 5-0 start and much of the reason is due to the play of Brown, the nation's leading rusher. Brown has totaled 906 rushing yards thus far this season and is on pace to break the 2,100-yard barrier. He's a nifty ballcarrier with the ability to create yardage on the inside or beat defenders around the corner. Brown, just a junior, projects as a top 45 selection in the draft.

Rashad Johnson/S/Alabama: Johnson has been key for the fast-rising Tide and one of Alabama's steadiest defenders this season. He leads the team with seven pass defenses, two which came against Georgia as Johnson helped prevent Bulldogs quarterback Matt Stafford from completing the long play during Alabama's victory. Johnson also ranks second on the Tide defense with 26 tackles, a testament to his well-rounded game.

Nate Davis/QB/Ball State: Davis leads one of the most potent offenses in the nation and his play has been spectacular this season. The junior has led his team to a 5-0 mark and is averaging just under 300 yards passing per game, while competing 72.5 percent of his throws. He's a smart, savvy NFL-type quarterback prospect with great intangibles.

Michael Tauiliili/LB/Duke: Tauiliili, a four-year starter, led the Blue Devils with 16 tackles and an interception in the teams 31-3 victory over Virginia, which marked Duke's first conference victory in more then three years. Tauiliili is averaging nearly 10 tackles per game and has been compared to former first-round pick Jon Vilma in size and style.

Sleeper Alert -- Purnell Sturdivant/OLB/Virginia Tech: Sturdivant became a full-time starter this season and is making the most of his opportunity. He ranks second on the team in tackles and has shown some mettle in pass coverage. Sturdivant hits the measuring tape at under six feet tall, yet has the skills to play for a one gap defense.

Sliders

Greg Middleton/DE/Indiana: The Hoosier junior was considered one of the better defensive line prospects coming into the season, yet his play has been poor. Indiana has given up a combined 84 points its last two games and Middleton has accounted for only four tackles. He's registered just a single sack this season and was easily neutralized by tight ends in IU's loss to Michigan State.

Cullen Harper/QB/Clemson: NFL scouting services graded Harper as the top senior quarterback entering the season, but thus far he has failed to live up to expectations. Harper has been suffering with a shoulder injury since the first game of the year, and it shows. He threw for just 151 yards in the loss to Maryland and has topped the 200-yard mark just once in five games.

Fili Moala/DT/USC: Moala's play has been disappointing this season, which was also the case last year. He was handled with relative ease against Oregon State, a line with players Moala should have had minimal problems overwhelming.

Curtis Painter/QB/Purdue: Painter's numbers this season have not been bad -- yet his play in the big spot leaves a lot to be desired, an issue that has long loomed over the Purdue signal-caller. Painter completed under 43 percent of his passes in the second half during the loss to Notre Dame, a game that was tied at halftime. Two weeks earlier, Painter could not get his team into the endzone during the final two quarters, as his team collapsed against Oregon.

Notes: NFL scouts realized it was a bleak year for quarterbacks before the season began, and the outlook continues to worsen. Curtis Painter and Cullen Harper are on this week's sliders list and Hunter Cantwell has done nothing to distinguish himself. After a solid showing against Kansas State, Cantwell threw and interception against Connecticut in the fourth quarter -- which was returned for the game winning score. Georgia's Stafford, who many think will be the first signal-caller drafted if he opts for the NFL, has done nothing to make scouts think he's worthy of being an early first-round pick.

Keep an eye on Mississippi defensive end Greg Hardy. A former member of the Rebel basketball team, Hardy is an outstanding athlete who's rounding into a good football player. After missing the early part of the season recovering from foot surgery, he was unstoppable in the upset win over Florida. Hardy led the teams with 2.5 tackles for loss, 1.5 sacks and also recorded a quarterback hurry. He's a prospect with great upside and a junior that could impact April's draft, if he leaves for the NFL.