Witherspoon spent all of last season playing for Double-A Arkansas, where he hit .214 with 11 home runs, 38 RBIs and 30 stolen bases in 129 games. The 6-foot-2, 190-pound right-handed hitter was a 12th-round selection in the 2009 Draft out of Spartanburg Methodist College and is regarded as a strong defender and excellent athlete with good speed and power potential who needs to develop his pitch recognition and on-base percentage.
Witherspoon was the 13th-ranked prospect in the Angels' organization in the latest MLB.com ratings. He is a native of Sumter, South Carolina.
Blanco, 42, was claimed off waivers by Seattle in mid-June to help mentor rookie catcher Mike Zunino and wound up batting .125 with three home runs and 14 RBIs in 35 games. The 16-year Major League veteran hit two grand slams for the Mariners, including one to beat Oakland in his Seattle debut June 15 and help Felix Hernandez to a 4-0 victory.
But Blanco finished the season in a 1-for-33 slump to finish at .142 for the year, including 15 games with the Blue Jays.
The Mariners now have 10 days to trade, release or outright Blanco.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.