The Red Sox designated outfielder Daniel Nava for assignment to create 40-man roster space for Drew Sutton, according to Alex Speier of WEEI.com (Twitter link). The Red Sox created room on the active roster for Sutton by optioning Jose Iglesias to the minor leagues.
Nava, 28, has a .192/.321/.262 line in 156 plate appearances at Triple-A this year. In 2010 he was a major contributor in Pawtucket, hitting .289/.372/.458 and earning a promotion to Boston. He made an impression early, hitting a grand slam on the first MLB pitch he saw and posting a .242/.351/.360 line in 188 plate appearances for the Red Sox.
Here's a more detailed look at Nava's path to the Major Leagues.