"First and foremost, Carlos brings us a veteran presence with outstanding leadership qualities and a winning pedigree," Dipoto said. "His combination of strong on-base skills, situational awareness and game-calling ability are a welcome addition to the Mariners."
But the departure of Nuno makes left-handed bullpen help a critical area of need going forward as the 29-year-old was the only southpaw who spent all of last year on the Mariners' staff, posting a 3.53 ERA in 55 appearances, including one spot start.
Dipoto already had left-handed relief as one of his primary targets this winter and his first trade of the winter leaves only 2015 Rule 5 Draft acquisition David Rollins and switch-pitcher Pat Venditte as lefty options on the 40-man roster, though Ariel Miranda could also compete for that role if he doesn't win a spot in the rotation.
Dipoto surely will beef up that competition in the coming weeks, but he targeted Ruiz in his first trade of the winter on the eve of MLB's General Manager Meetings in Scottsdale, Ariz.
Ruiz spent the first 10 1/2 seasons of his career with the Phillies -- a run that included a World Series title in 2008 and a second National League pennant the following year. He was traded to the Dodgers for catcher A.J. Ellis and Minor Leaguers Tommy Bergjans and Joey Curletta on Aug. 25.
Ruiz has a career line of .266/.352/.393 with 68 home runs and 404 RBIs in 1,083 games. He hit .264/.365/.348 with three homers and 15 RBIs in 62 games last season, with the last 14 of those coming with the Dodgers. He went 3-for-11 in seven postseason games for Los Angeles, including a pinch-hit home run in Game 3 and the go-ahead RBI single in Game 5 of the National League Division Series against Washington.
Ruiz's contract includes a $4.5 million option for 2017, which the Mariners exercised. Iannetta would have made $4.25 million if the Mariners had picked up his option.
Ruiz's .365 on-base percentage this season ranked fourth among MLB catchers with at least 200 plate appearances. Defensively, he led NL catchers this season in caught stealing percentage at 41.7 percent (15-for-36) and he is a well-regarded clubhouse presence as well.
Ruiz is one of two catchers in Major League history -- along with Jason Varitek -- to catch four no-hitters.
Nuno was acquired by Seattle in midseason of 2015 from the D-backs, along with Mark Trumbo, in a six-player deal. In parts of two seasons with the Mariners, he went 2-5 with a 3.85 ERA in 87 games, including 11 starts.
In his four-year MLB career, Nuno is 5-20 with a 4.02 ERA in 126 games, including 42 starts, with the Yankees, D-backs and Mariners.