Guillen signed a one-year contract with the Mariners last month, but became expendable with the addition of Aurilia, who signed a one-year, $3.5 million contract.
"When we signed Carlos, it was with the idea that he would be our starting shortstop," said General Manager Bill Bavasi. "The Rich Aurilia signing changes that."
Guillen, 28, raised his average for the fourth straight season in 2003, batting .276 with seven home runs and 52 RBI in 109 games. He gives the Tigers a solid double play combo with Fernando Vina.
With San Francisco last season, Aurilia hit .277 with 13 homers and 58 RBI. He career .278 hitter has 126 homers and 473 RBI.
(Rich Aurilia) is a guy who has been a power-productive shortstop and we have been looking at more production (at shortstop)," said Seattle General Manager Bob Melvin. "We feel this is the guy."