Middlebrooks, obtained by general manager A.J. Preller last winter, was optioned on July 21 to Triple-A El Paso, where he hit .255. Middlebrooks wasn't added to the roster in September, which may have signaled the end of his time with the organization.
The Padres also avoided arbitration with infielder Brett Wallace, signing him to a one-year deal for $1 million.
Wallace, who signed with the Padres last winter as a Minor League free agent, hit .302 in 64 games after being recalled from El Paso on June 19. He hit five home runs and drove in 16 runs. Four of those home runs were as a pinch-hitter.
Had the Padres not tendered contracts to those players by 9 p.m. PT, they would have become free agents.
The date for salary-arbitration filing is Jan. 12, and the players and teams exchange figures on Jan. 15, with hearings to be held Feb. 1-21.
Prior to Wednesday's deadline, the Padres moved two players who were on the bubble to be non-tendered.
The Padres sent first baseman Yonder Alonso and left-handed reliever Marc Rzepczynski to the A's for Pomeranz and Minor League left-hander Jose Torres, along with cash considerations or a player to be named.
It hasn't been determined if Pomeranz will start or pitch in relief, Preller said. It's something pitching coach Darren Balsley, manager Andy Green and new bullpen coach Doug Bochtler will discuss in the coming weeks.
"It's a big body, a lefty that throws in the low 90s with a breaking pitch," Preller said. "I think the versatility, left-handed, he has had a good track record the last few years, was all appealing."
According to MLBTradeRumors.com, here are the estimates of what the Padres' arbitration-eligible players could make: Cashner ($7 million), Ross ($10 million) and Norris ($3.4 million).
Gale made his big league debut last September at the age of 27. He had one hit in 10 at-bats.
Garces had a 5.21 ERA over 40 games and allowed nine home runs in 38 innings, four to left-handed batters.
Preller indicated late Wednesday that the team has an interest in re-signing Gale, Garces and Middlebrooks to Minor League deals, if they're interested.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.