Freitas, 26, was a 15th-round pick by the Nationals in 2010. He was dealt to the Orioles in 2013 as part of the Jim Johnson trade, and he spent most of last season at Double-A Bowie, where he batted .242 in 71 games with eight homers, 12 doubles and 33 RBIs.
The Cardinals selected O'Neill, 27, in the 31st round of the 2010 Draft, and the left-handed hitter had a combined .289 batting average in 90 games last season at Double-A Springfield and Triple-A Memphis. He has a career .412 on-base percentage.
Loya, 23, a left-handed hitter, spent last season in Mexico, where he batted .