• Mariners Spring Training info
Aro, 25, was an intriguing pitcher in camp, landing with the Mariners in the trade with the Red Sox that also brought veteran lefty Wade Miley. Aro pitched at three levels last year, including six appearances for the Sox.
"We're really happy we acquired him this offseason," Mariners manager Scott Servais said. "He got off to a little bit of a rocky start in camp, but he threw really well his last time out. Again, he kind of went very fast last year ... but he's a guy I think we'll work into our bullpen mix at some point. He needs a little more time."
Servais also said Sampson "jumped up the depth chart" and figures to be part of the Tacoma rotation, Rollins will continue his progress as a lefty specialist, and Baron was one of the most improved players in camp.
Lucas, a non-roster invitee who got Major League time with the Marlins in 2013-14, hit .290 in 31 at-bats and six runs scored in Cactus League play. The 34-year-old will head to Tacoma, where Servais expects he'll provide leadership there and insurance for the Mariners if they need his utility skills.
The Mariners have 20 pitchers (five non-roster invitees), three catchers, 10 infielders (two NRI) and seven outfielders (one NRI) in camp, plus two players on the 60-day disabled list after Sunday's moves.
"I thought all those guys showed well at times in camp," Servais said. "But the innings and at-bats are starting to go away, so we wanted to let those guys go down and get ready for their seasons.''
John Schlegel is a national reporter for MLB.com. You can follow hium on Twitter @JohnSchlegelMLB. This story was not subject to the approval of Major League Baseball or its clubs.