Darvish was 13-9 with a 2.93 ERA in 32 starts last season. He led the majors with 277 strikeouts and was second in the AL Cy Young Award voting.
Baker has started games at first, second and third base and in the outfield. The 35-year-old Robertson last pitched in the majors in 2010.
Michael Young was a leader on a Rangers team that reached the World Series in 2010 and 2011. He agreed to the trade rather than accept a utility role in Texas.
After two consecutive trips to World Series, Rangers end season with loss in wild card game. Fans talk to NBC 5's Scott Gordon about the season ender.
Texas (92-66) saw its division lead over the A's cut to two games with four to play.
Hamilton was not with the Rangers for their weekend series in Seattle.
For the second straight night, the Texas Rangers were well aware there was an opportunity to make their lead in the AL West a bit more comfortable, and they failed.
Rangers beat Seattle 2-1, adding to their AL West lead over Oakland for the first time in 10 days.
Texas had won six consecutive series. ... Oswalt has given up 11 homers in 54 1-3 innings this season. ... LHP Miguel De Los Santos, placed on waivers by Texas on Thursday, was claimed by Milwaukee.
Rangers C Mike Napoli (left quadriceps) is set to join Double-A Frisco for a rehab assignment. ... Texas reliever Alexi Ogando has been slowed the past few days because of biceps tightness.