De Los Santos, 26, was optioned to Triple-A Nashville. To make room for him on the 40-man roster, the team shifted right-hander Shaun Marcum to the 60-day disabled list.De Los Santos, 26, has a 4.21 ERA and 46 strikeouts in 36 1/3 innings for the A's over the past two seasons, including 34 appearances in 2011 and six this year. Big league opponents batted only .220 against him last season but were 7-for-17 in very limited duty this April. De Los Santos had been at Triple-A Sacramento since then, pitching to a 7.25 ERA and a .320 opponents' average in 28 games. He had been pitching well in July before allowing three hits, a walk and three earned runs on Tuesday at Salt Lake City. He has not pitched since then.
"He's got big velocity and has struggled at times with his command, but in a deal like this, it is a chance to get an upside arm," Ash said. "[The A's] had expressed interest [in Kottaras] and we gave them a couple of names, and this was one we agreed on. Our scouts saw him and liked his arm; I know he hasn't had great results this year, but there's some upside."
De Los Santos will be out of options beginning next year.