Originally Published: October 7, 2013

Which quarterbacks get a passing grade?

By Mark Schlabach | ESPN.com

We're almost halfway through the "Year of the Quarterback" in college football, and if the first six weeks of the 2013 season revealed anything, it's that a quarterback will probably win the Heisman Trophy and the position will carry more importance than ever in the BCS national championship race.

Of the top 15 quarterbacks in ESPN's QBR, 11 players are starting for teams currently ranked in the top 15 of the Associated Press poll, including seven starters (and one backup, Ohio State's Kenny Guiton) of undefeated squads.

The Total Quarterback Rating, also known as Total QBR or QBR, was introduced by ESPN this season. Because college football has unbalanced schedules (hello, Baylor and Ohio State!), QBR is also adjusted to account for the strength of the defenses a quarterback has faced to formulate Adjusted QBR.

The scale of QBR is from 0 to 100, on which 50 is average, and measures all quarterback contributions to scoring, taking into account game context on a play-by-play level, such as down, distance, field position, as well as clock and score.

For instance, a 5-yard gain on third-and-4 is a good play, whereas a 5-yard gain on third-and-14 isn't. A 20-yard touchdown pass when the score is tied in the second quarter means more than a 20-yard touchdown pass when a team is down (or up) 30 points late in the fourth quarter.

Top quarterbacks are typically in the upper 80s and 90s for a season. Reigning Heisman Trophy winner Johnny Manziel of Texas A&M ranked first in QBR in 2012 with a value of 90.5. His unadjusted value was 86.4, also the highest mong quarterbacks of FBS schools. There wasn't much of a difference between Manziel's Total QBR and Adjusted QBR, reflecting that the Aggies played pretty good defenses last season.

Here's a closer look at the top quarterbacks in college football this season, based on Adjusted QBR:

1. Bryce Petty, Baylor
Adjusted QBR: 97.7 (first overall)
Statistics: 72.8 percent completion percentage, 1,348 yards, 10 touchdowns, 1 interception

Stats that matter: Petty hasn't yet faced an opponent that ranks in the top 75 nationally in scoring defense, but what he's done in four games this season would be difficult to do in practice. The No. 15 Bears are averaging 779.5 yards and 70.5 points per game. Petty is averaging 14.6 yards per attempt, highest among FBS quarterbacks. Even more impressive, he's completing 12 of 14 passes for 320 yards with 11 first downs on third down. In fact, you won't find a better quarterback on third down than Petty. He has the highest QBR on third down (100.0), just ahead of Manziel and Oregon's Marcus Mariota. Baylor is the only team in the country that hasn't snapped three downs and punted. The Bears did turn the ball over once before making a first down and have taken a couple of end-of-half kneel-downs but no three-and-out punts.

Best win: 73-42 over West Virginia, Oct. 5
Toughest remaining test: vs. Oklahoma, Nov. 7

2. Marcus Mariota, Oregon
Adjusted QBR: 96.8 (second overall)
Statistics: 56.7 percent completion percentage, 1,358 yards, 14 touchdowns, 0 interceptions
Stats that matter: Mariota accounted for a school-record seven touchdowns (five passing, two rushing) in 2½ quarters of the No. 2 Ducks' 57-16 victory at Colorado on Saturday. Mariota, a sophomore from Honolulu, has posted a Total QBR of 90 or more in four of five games this season. Mariota has gone 202 pass attempts without an interception, breaking the former Oregon record set by Kellen Clemens of 178 in 2004. Mariota's last pick came in the second quarter against Stanford on Nov. 17, 2012. He also has the highest QBR on rushing plays (100).
Best win: 59-14 over Tennessee, Sept. 14
Toughest remaining test: at No. 5 Stanford, Nov. 7

3. Aaron Murray, Georgia
Adjusted QBR: 95.6 (third overall)
Statistics: 64.9 percent completion percentage, 1,534 yards, 14 touchdowns, 3 interceptions

Stats that matter: Murray, who was criticized before this season for his inability to lead the Bulldogs to big victories, has a 96.5 Total QBR when trailing this season, highest among FBS quarterbacks with at least 20 action plays. Murray had an 84.7 Total QBR in No. 7 Georgia's come-from-behind, 34-31 overtime victory at Tennessee on Saturday and completed five of nine passes on its final drive in regulation, including the tying 2-yard touchdown pass to Rantavious Wooten with five seconds to go.
Best win: 44-41 over LSU, Sept. 28
Toughest remaining test: vs. No. 17 Florida, Nov. 2

4. Zach Mettenberger, LSU
Adjusted QBR: 92.3 (fifth overall)
Statistics: 68.2 percent completion percentage, 1,738 yards, 15 touchdowns, 2 interceptions
Stats that matter: How much of a difference has new LSU offensive coordinator Cam Cameron made in Mettenberger's development this season? A year ago, the UGA transfer had a 27.2 opponent-adjusted QBR through the first six games of the season. Through six games this season, Mettenberger has an 92.3 adjusted QBR. He threw for more than 300 yards in each of the past two games against Georgia and Mississippi State after failing to accomplish the feat in 13 games in 2012.
Biggest win: 35-21 over Auburn, Sept. 21
Toughest remaining test: at No. 1 Alabama, Nov. 9

5. Jameis Winston, Florida State
Adjusted QBR: 91.6 (sixth overall)
Statistics: 73.2 percent completion percentage, 1,441 yards, 17 touchdowns, 2 interceptions
Stats that matter: "Famous" Jameis Winston, FSU's sensational redshirt freshman, completed 23 of 32 passes for a career-high 393 yards with five touchdowns in No. 6 Florida State's 63-0 win over Maryland on Saturday. The Terps were one of the country's best defenses statistically; their previous four opponents had a combined Total QBR of 12.7, which was the lowest Total QBR allowed by a defense entering the weekend. Winston had a 90.4 Total QBR against the Terrapins, his fifth straight game with a Total QBR of 75 or higher. In the past 10 seasons, Winston is only the second player to post a Total QBR of at least 75 in his first five career games. Boise State's Kellen Moore also did it in 2008.
Biggest win: 63-0 over Maryland, Oct. 5
Toughest remaining test: at No. 3 Clemson, Oct. 19

6. Johnny Manziel, Texas A&M
Adjusted QBR: 89.1 (seventh overall)
Statistics: 71.4 percent completion percentage, 1,489 yards, 14 touchdowns, 4 interceptions
Stats that matter: How valuable has Johnny Football been to Texas A&M's offense the past two seasons? Last season, when he became the first freshman to win the Heisman Trophy, he led the Aggies to points on 58 percent of his possessions. This season, he's led Texas A&M to points on 65 percent of his drives, scoring on 30 of 46 possessions when he's on the field. Manziel has been exceptionally good on third down, with a QBR of 99.5 that is second only to Petty's 100.
Biggest win: 45-33 over Arkansas, Sept. 28
Toughest remaining test: at No. 10 LSU, Nov. 23

7. Teddy Bridgewater, Louisville
Adjusted QBR: 88.6 (eighth overall)
Statistics: 71.7 percent completion percentage, 1,562 yards, 16 touchdowns, 1 interception
Stats that matter: Bridgewater has quietly put together one of the most consistent seasons of any FBS quarterback, albeit against a very soft schedule. He ranks sixth among FBS quarterbacks in QBR on 3rd down (96.6) and third in QBR on passing plays (96.5). Bridgewater passed for 348 yards with two touchdowns in the Cardinals' 30-7 victory over Temple on Saturday, completing passes to 10 different receivers. He has thrown a touchdown pass in 17 consecutive games, tying Dave Ragone's school record set in 2001-02.
Biggest win: 27-13 over Kentucky, Sept. 14
Toughest remaining test: vs. UCF, Oct. 18

8. Blake Bell, Oklahoma
Adjusted QBR: 85.4 (12th overall)
Statistics: 69.2 percent completion percentage, 835 yards, 6 touchdowns, 0 interceptions
Stats that matter: Since replacing Trevor Knight as the Sooners' starting quarterback in the third game, Bell has hardly resembled the "Belldozer" that plowed over opponents the past couple of seasons. Bell has attempted 30 passes in each of the past three games, averaging 265.6 passing yards with six touchdowns and no interceptions in 98 attempts. He has run the ball less than 15 times in each of the three games but did run for a season-high 61 yards on 14 carries in a 20-17 win over TCU on Saturday.
Biggest win: 35-21 at Notre Dame, Sept. 28
Toughest remaining test: at No. 15 Baylor, Nov. 7

9. Kevin Hogan, Stanford
Adjusted QBR: 85.1 (13th overall)
Statistics: 62.6 percent completion percentage, 932 yards, 11 touchdowns, 4 interceptions
Stats that matter: The No. 5 Cardinal probably ask its quarterback to do less than any of the championship contenders, but Hogan is really good at what he does. He is 10-0 as a starter since replacing Josh Nunes last season, including a 6-0 record against ranked foes. Hogan has passed for less than 200 yards in three of five games this season but had a season-high 286 yards in a 55-17 rout of Washington State on Sept. 28.
Biggest win: 31-28 over Washington, Oct. 5
Toughest remaining test: vs. No. 2 Oregon, Nov. 7

10. Tajh Boyd, Clemson
Adjusted QBR: 77.8 (27th overall)
Statistics: 66 percent completion percentage, 1,449 yards, 14 touchdowns, 2 interceptions
Stats that matter: Boyd ranks 16th in raw QBR and 27th in adjusted. Regardless, he guided the No. 3 Tigers to a 38-35 upset of Georgia in the opener and then threw for a career-high 455 yards with five touchdowns in a 49-14 rout at Syracuse on Saturday. Boyd now has 87 career touchdown passes, which is eight behind former NC State star Philip Rivers' ACC record of 95. Boyd has also accounted for 107 touchdowns in his career, which is 5 behind Rivers' ACC record.
Biggest win: 38-35 over Georgia, Aug. 31
Toughest remaining test: vs. No. 6 Florida State, Oct. 19

11. AJ McCarron, Alabama
Adjusted QBR: 67.6 (52nd overall)
Statistics: 71.4 percent completion percentage, 1,048 yards, 10 touchdowns, 3 interceptions
Stats that matter: Alabama's rebuilt offensive line has struggled to protect McCarron at times this season, but he's still putting up eye-popping numbers. In the Tide's two games against ranked opponents, McCarron completed 45 of 61 passes for 514 yards with four touchdowns in victories over Texas A&M and Ole Miss. He guided the Tide to each of the past two BCS national championships and has a 29-2 record as a starting quarterback. In Saturday's 45-3 victory over Georgia State, McCarron set an Alabama single-game record by completing 93.7 percent of his passes (15-for-16), breaking the record of 84.2 percent (16-for-19) set by Ken Stabler against Ole Miss in 1966. Overall, 12 of his 16 attempts went for a first down or touchdown, the highest percentage by a quarterback in a game this season.
Biggest win: 49-42 at Texas A&M, Sept. 14
Toughest remaining test: vs. No. 10 LSU, Nov. 9

12. Braxton Miller, Ohio State
Adjusted QBR: 59.3 (66th overall)
Statistics: 65.3 percent completion percentage, 609 yards, 6 touchdowns, 2 interceptions
Stats that matter: Miller, who came into the season as a Heisman Trophy candidate, missed most of three games with a knee injury. In fact, Kenny Guiton, who replaced him in three games, has a much higher QBR (81.6). Miller passed for 203 yards and ran for 68 in the No. 4 Buckeyes' 40-30 victory at Northwestern on Saturday night, but he also lost two fumbles and threw an interception.
Biggest win: 40-30 at Northwestern, Oct. 5
Toughest remaining test: at No. 18 Michigan, Nov. 30

On the Mark

Ball State coach Pete Lembo's résumé probably won't get too many FBS athletic directors excited, but they might want to take a closer look at his track record. After producing winners at Lehigh and Elon, Lembo guided the Cardinals to a 9-4 record last season. They're 4-1 this season, including a 48-27 rout at Virginia on Saturday.

The Cardinals piled up 506 yards of offense and outscored the Cavs 31-10 in the second half. Before Lembo replaced Brady Hoke at Ball State, the Cardinals had one victory over an opponent from a BCS conference (Indiana in 2008). Lembo has guided them to four such victories in less than three seasons (they also beat the Hoosiers in 2011 and '12 and USF last season).

"This has got to be the biggest win in the history of Ball State football in 90 years," Lembo said. "We've had three BCS wins the last two years, but nothing compares to this, coming on the road, to Virginia, beating an ACC opponent."

Off the Mark

We love what Washington coach Steve Sarkisian is doing with the Huskies this season, but he all but accused Stanford's players of faking injuries to slow down his offense's pace in a 31-28 loss on Saturday night.

"Their defensive line coach [former UW assistant Randy Hart] was telling them to sit down," Sarkisian said during his postgame radio show, according to published reports. "I guess that's how we play here at Stanford, so we'll have to prepare for that next time. At some point, we'll get repaid for it. That never serves a purpose for us, and we'll never do that."

Cardinal linebacker Shayne Skov was down for a few minutes in the second half after injuring his right knee.

"Took a shot," Skov told the San Jose Mercury News. "It's football. Sometimes, you get hit. I'm fine, but needed a moment to take care of it."

On the Mark

Missouri is off a 5-0 start and is back in the national rankings after a 51-28 rout at Vanderbilt. After a disappointing 5-7 finish in their first season in the SEC in 2012, the Tigers are healthy on the offensive line and getting solid play from quarterback James Franklin.

"This doesn't surprise me," Missouri coach Gary Pinkel said. "Everybody's going, 'Wow!' All of a sudden, everybody loves James Franklin. I loved him last year and his sophomore year. I'm very proud of him and how he's playing, how he's competing, how he's seeing things."

The Tigers are a lot better on defense, too, thanks to senior defensive end Michael Sam. Sam, a senior from Hitchcock, Texas, has posted three sacks in each of the past two games. The No. 25 Tigers will have an opportunity to make a big statement when they travel to No. 7 Georgia to play the depleted Bulldogs on Saturday.

Off the Mark

It's a shame we won't get to see much of the country's best player this season. South Carolina coach Steve Spurrier was peeved that defensive end Jadeveon Clowney didn't tell him he wasn't going to play in Saturday's game against Kentucky until shortly before kickoff. The No. 14 Gamecocks probably could have used him in a closer-than-expected 35-28 victory.

Clowney had a rib injury that hampered him in practice last week, but the Gamecocks believed he was ready to go. Clowney has also missed time because of an illness before the opener against North Carolina, flu against UCF and chronic pain from bone spurs in his right foot.

"We didn't know he wasn't playing until right before the game," Spurrier said on Sunday. "That was a little frustrating. Usually, the trainer or the doctor tells you, 'This guy's out.' That did not happen last night."

Even Spurrier has to wonder if the distractions haven't gotten into Clowney's head about staying healthy before next spring's NFL draft. Asked about Clowney's commitment to playing this season, Spurrier replied: "You'll have to ask him that. I can't speak for Jadeveon."


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