Sardinas, 22, spent parts of the past two seasons in the Majors with the Rangers and Brewers, batting .231 with six doubles, a triple and five stolen bases in 79 games. The speedy switch-hitter is well-regarded defensively, and he provides depth behind Ketel Marte at shortstop for Seattle and can also play second and third base.
Sardinas played for new Mariners bench coach Tim Bogar in Texas in 2014, when Bogar was the bench coach and interim manager for the Rangers, putting up a .261/.303/.313 line with six doubles in 115 at-bats over 43 games.
Sardinas also knows new Mariners manager Scott Servais from his time as farm director of the Rangers and said that familiarity is welcome.
"I am happy to work with them and that's what you are looking for, to be comfortable," Sardinas said in a statement through his agency. "The best thing about the Mariners is they have a lot of Latin players. That's always the hardest thing when you get traded. Today, we are in a place and tomorrow, you don't know.
"If this happens to me, it's because this is a new opportunity to keep fighting for my dream and play every day in Major League Baseball."
Sardinas was one of three youngsters dealt from Texas to Milwaukee for pitcher Yovani Gallardo last January, but Sardinas hit just .196 in 36 games in two stints with the Brewers. Sardinas spent most of the season with Triple-A Colorado Springs, where he hit .282 with 17 doubles, five triples, one home run and 16 stolen bases in 103 games.
Flores, 23, was acquired from the Yankees along with reliever Jose Ramirez on July 30 in a trade for Dustin Ackley and hit .423 in 14 games for Triple-A Tacoma before breaking his right ankle on Aug. 14 when he slipped on wet grass in the Cheney Stadium outfield. Flores had surgery to repair a compound fracture and missed the remainder of the season.
Flores is out of Minor League options and would have had to either make the Mariners' 25-man roster next season or be exposed to waivers. Sardinas has one Minor League option remaining.
Prior to being acquired by Seattle, Flores played in 12 games for the Yankees last season, batting .219 (7-for-32) and also hit .286 in 73 games for the Yankees' Triple-A Scranton/Wilkes-Barre club. He was the No. 25-ranked prospect in the Mariners organization, according to MLB.com's Pipeline.
Sardinas no longer qualifies for prospect status because of his Major League service time, but he was rated the No. 2 prospect in the Rangers' system by MLB.com during 2013-14 and No. 71 among all prospects in MLB at that time.
Since taking the Mariners' reins, Dipoto has now dealt nine players -- including five from the Major League roster -- and acquired seven back.
Seattle swapped shortstop Brad Miller, first baseman Logan Morrison and reliever Danny Farquhar to the Rays for pitchers Nathan Karns and C.J. Riefenhauser and Minor League outfielder Boog Powell on Nov. 5.
Dipoto then acquired veteran reliever Joaquin Benoit from the Padres for Minor Leaguers Enyel De Los Santos and Nelson Ward on Nov. 11, before dealing reliever Tom Wilhelmsen, outfielder James Jones and a player to be named for outfielder Leonys Martin and right-hander Anthony Bass on Monday.