BOSTON - The Boston Red Sox have designated outfielder Daniel Nava for assignment in a move to add pitching depth.

The Red Sox recalled right-handed reliever Jonathan Aro from Triple-A Pawtucket on Thursday to take Nava's place. Boston also optioned left-handed reliever Tommy Layne to Triple-A to make room for right-hander Jean Machi, who was claimed off waivers from San Francisco this week.

Nava was a key contributor on Boston's 2013 World Series title team, hitting .303. But his numbers and playing time diminished the past two seasons. Hampered by a thumb injury, the 32-year-old Nava hit .152 in 29 games this season.

Aro has a 2.95 ERA in 25 minor league appearances this season.

Layne has a 3.51 ERA in 40 relief appearances with Boston in 2015.

The Red Sox also sent catcher Sandy Leon to Pawtucket after he cleared waivers.