Volquez presumably would be an alternative to fifth starter Chris Capuano, who was been inconsistent this year, although Capuano's 4-7 mark with a 4.74 ERA is arguably better than Volquez's stats.
Volquez also could serve as a sixth starter, instead of Stephen Fife, to give the rotation extra rest.
At the forefront of Volquez's problems this year, San Diego pitching coach Darren Balsley said, were his emotions, especially when he got into a game.
"We worked hard mechanically on keeping him on a good line toward home plate; we tried to shorten up his stride and get him to be a little taller. In his bullpen sessions, he could do it. But in the game, he basically overthrew," Balsley said. "That led to mechanical breakdowns.
"And it's hard to tell someone not to try so hard. He's very competitive. His competitive nature gets the best of him."
Volquez went 11-11 with a 4.14 ERA and made 32 starts for the Padres a year ago. But opponents hit .236 against him a year ago. This season, they were hitting .291 with an .820 OPS. His strikeout rate per nine innings (7.33) was the lowest in any full season he has pitched in the big leagues.
Balsley is hopeful that Volquez, despite his issues with the Padres, can turn things around -- even if for a different team.
"He's what, 30? He's still young," Balsley said. "Moving on, I expect him to hook on quickly with another team. Once he gets his emotions under control, he's going to be a very good pitcher."
Ken Gurnick is a reporter for MLB.com. Corey Brock contributed to this story. This story was not subject to the approval of Major League Baseball or its clubs.