In two seasons at Coffeyville, Carpenter started every game at left tackle for the Red Ravens and earned All-Conference (KJCCC) honors twice. In 2008 he was named to the NJCAA All-American first team.
Rated as a four-star recruit by Rivals.com, Carpenter was ranked as the No. 32 junior college prospect in 2009.
Although he remained an Iowa State signee, he began visiting other schools "just […] to make sure I make a good decision". He made official visits to Texas Tech, Oklahoma and Ole Miss, before eventually committing to Alabama.
Carpenter faced the difficult task to replace All-American left tackle Andre Smith. While analysts did not expect him to dominate as a run blocker like Smith, they saw him as "a rock in pass protection".
Carpenter went on to start every game at left tackle for the Crimson Tide in 2009 and 2010.
Carpenter had a good post-season performance and, according to Sports Illustrated, went "from a third-round choice to a player who could be a surprise pick late in round one". He was selected with the 25th overall pick in the 2011 NFL Draft by the Seattle Seahawks. Carpenter started 9 games in his rookie season before suffering a season ending ACL injury and being placed on the injured reserve.