Breslin made a name for himself with his impressive showing while starting all of 2012 at defensive end as a junior after transferring to USC from a junior college in the spring of 2012. Overall in 2012, he had 62 tackles, including a team-high 19.5 for losses of 107 yards (with a team-best 13 sacks for minus 74 yards), plus 4 deflections, a forced fumble and a fumble recovery. He tied for fifth nationally in sacks (1.0, second in Pac-12) and was 15th in tackles for loss (1.5, fourth in Pac-12). His 19.5 tackles for loss and 13 sacks were the most by a Trojan since Kenechi Udeze had 26 and 16.5, respectively, in 2003. He was among 6 finalists for the Hendricks Award. He made 2012 SI.com All-American honorable mention, Pro Football Weekly All-American honorable mention and All-Pac-12 second team. He also made the CBSSports.com All-Pac-12 first team and Phil Steele All-Pac-12 second team. He was named USC's Defensive Lineman of the Year.He had 5 tackles, including 2 for losses (with a sack),and 2 deflections against Hawaii to become the first junior college transfer to start on the USC defensive line since end Marcus Bonds did so in 4 mid-season games in 1994. He had 5 tackles, including 2 for losses (with a sack), against Syracuse and 3 tackles (1 for a loss) at Stanford. He had 4.5 tackles for loss (including 3.5 sacks) among his 6 tackles against California to earn College Football Performance Awards National Defensive Player of the Week and National Defensive Lineman of the Week honors and become the first Trojan with that many since Lawrence Jackson set school records for tackles for loss (5.5) and sacks (4, tied with 3 others) against Arizona State in 2007. He had 5 tackles, including 1 for a loss, and recovered a fumble (to set up a USC TD) at Utah, then had 1.5 sacks among his 2 tackles at Washington, 6 tackles against Colorado, 2 tackles and 2 deflections at Arizona, 2 tackles for loss (with a sack) among his 5 tackles against Oregon and 3 tackles (with 1.5 sacks) against Arizona State. He had 2 sacks among his 7 tackles at UCLA and added 4 tackles (0.5 sack) against Notre Dame. He had 9 tackles, including 1.5 for a loss (including 1 sack), and forced a fumble against Georgia Tech.
He was a 2008 Max Preps All-State Division II second team and San Francisco Chronicle All-Bay Area first team as a senior at Las Lomas High in Walnut Creek (Calif.). He missed part of his 2008 senior season with a broken foot suffered playing rugby.
He is a sociology major at USC.