Louisville and coach Bobby Petrino is winning with defense. Yes, that’s right. One of college football’s top offensive minds has turned to the dark (defensive) side to win games in 2014.



Petrino’s arrival was expected to keep Louisville’s offense among the best in the ACC this year, but the Cardinals rank seventh in its new conference in scoring (33.3 ppg) and average 5.2 yards per play.



But if you remove the non-conference slate, Louisville’s offense ranks in the middle of the ACC.



The Cardinals are averaging just 4.8 yards per play through four conference contests and have scored above 25 points only twice in the ACC.



A struggling offensive line is largely to blame for Louisville’s problems on offense this season. Despite having four starters, the Cardinals have allowed 19 sacks – including 14 in four ACC games. That’s on pace to easily shatter last year’s mark (26), while rushers are averaging only 3.8 yards per play.



In addition to the offensive line, the increased competition, coaching change and quarterback carousel have all factored into Louisville’s offense not taking off in 2014.



While the offense is struggling, Louisville’s defense has carried this team through the first six games.



The Cardinals lead the ACC by holding opponents to 12.7 points per game and have allowed just four touchdowns in four conference games. New coordinator Todd Grantham’s defense is also allowing just 3.8 yards per play after giving up 4.2 in 2013. Total yardage can be a misleading statistic, but Louisville has not allowed an opponent to reach 300 yards in a game this year.



The Cardinals have been aggressive around the line of scrimmage, ranking fourth in the ACC with 44 tackles for a loss, third in the conference in sacks (21), and the defense has forced 15 turnovers (second-most in ACC).



Adding to the impressive start for Louisville’s defense is the unit had to transition to a 3-4 scheme after operating out of a 4-3 under Charlie Strong.

Despite four returning starters, this unit has managed to build off a strong finish to 2013. Rush end linebacker Lorenzo Mauldin is off to a fast start (26 tackles, 9 TFL, 4 sacks), but the senior has help from sophomore Keith Kelsey (37 stops), junior lineman Sheldon Rankins (three sacks), while James Sample, Gerod Holliman and Terell Floyd have solidified the safety position, which was arguably the biggest concern for the defense entering 2014.



Grantham’s hire was met with some skepticism after Georgia allowed 29 points per game in 2013. However, Grantham has been able to blend the returning personnel to his 3-4 fit and has Louisville’s defense ranked near the top of the ACC in key defensive categories.



But there’s a key challenge coming for Louisville and Grantham: The schedule. After playing just one offense ranked inside of the top 55 of Football Outsiders S&P offensive ratings, the Cardinals will play six the rest of the year. Louisville will play three potential All-ACC quarterbacks in Jameis Winston, Deshaun Watson and Jacoby Brissett in October.



There’s no doubt the competition and quarterback play will increase over the second half of the season. But so far, Grantham and Louisville appears to be up for the challenge, especially if the defense can continue to create havoc at the line of scrimmage and force turnovers.



Also, Louisville’s offense should improve through the final six games. The Cardinals’ offensive line remains a concern, but freshman Reggie Bonnafon or sophomore Will Gardner are capable quarterbacks for Petrino’s offense. Bonnafon and Gardner also have additional help in the form of receiver DeVante Parker potentially returning to the lineup this week against Clemson.



The Cardinals are off to a 5-1 start in their first year of ACC play and are set to finish the year with a challenging six-game slate, including a road trip to Clemson this Saturday, followed by games against Florida State, Notre Dame and rival Kentucky in the finale.



In an odd twist, Louisville’s defense is carrying this team through the first six games. The Cardinals need their defense to keep performing at the current pace, while getting more from the offense if they want to knock off Florida State or Clemson in ACC play in 2014.



Petrino will eventually get the offense on track. But until that happens, Louisville is poised to use its defense to navigate a difficult schedule in the second half of the season.