Most improved units: NFC

Morris Claiborne and Brandon Carr should greatly improve the Dallas secondary. US Presswire

With the NFL draft and the better portion of free agency behind us, most teams have made their biggest moves to improve their rosters for the 2012 season. Looking at the additions so far, I see several key units that have been improved this offseason. On Friday, I'll examine those units in the AFC, but for now, let's start with the Dallas Cowboys and the NFC.

Dallas Cowboys

This was a bad unit in 2011, with few big plays versus good passing games. It recorded only 15 interceptions, and a lot of offenses really attacked Dallas successfully on the edges of the defense.