Neither Byrd nor Parker has played in the majors.
The A's selected Parker in the fifth round of the 2009 MLB Draft out of BYU. After signing, he began his professional career playing rookie-ball and with Oakland's low-A team before making the jump to high-A in his first full season. That year he hit .296/.392/.508 with 38 doubles, five triples and 21 home runs.
Parker's production has tailed off over the past two seasons, as he's moved up to the ranks to Double- and Triple-A. Over 375 plate appearances in 2012 he hit .256/.327/.390 with 13 doubles, five triples and seven home runs. In four seasons in the minors the 25-year-old has hit .277/.361/.429.
Byrd was selected by the Philadelphia Phillies in the 18th round of the 2005 MLB Draft out of highschool. He spent his first four seasons as a professional with the Phils before joining the Brewers in 2010. Last year he maintained an ERA of 2.59 with a 1.97 strikeout-to-walk ratio over 50 appearances for Milwaukee's Double-A team. The 26-year-old owns a career ERA of 3.69 over eight seasons in the minors.