"It relates to the Rule 5 Draft, so I can't sort of reveal all the information until we get to tomorrow, but I think it'll be clear after tomorrow," he said.
Astros general manager Jeff Luhnow was asked about the trade's relation to the Rule 5 Draft. "We can't comment on who the players to be named later are or when that's going to occur, but it will reveal itself over time," he said.
The acquisition of Bass doesn't fill the Astros' need for a veteran relief pitcher, which is why the club is pushing to acquire Veras, who signed with Houston a year ago, then was traded to the Tigers in July. There was some hope the sides would come to an agreement on Wednesday, but Veras' camp turned down an initial offer.
Veras told MLB.com on Tuesday he would like to return to Houston, and Luhnow has previously acknowledged he was a good fit. He declined to discuss Veras when asked Wednesday.
"I'm not going to comment on specific players we haven't reached an agreement with, but we are looking for options to improve our pitching, and Bass is a nice option," Luhnow said.
Bass, 26, made 24 appearances, pitching 42 innings in four stints out of the Padres' bullpen in 2013. He also spent three months at Triple-A Tucson, where he made 15 starts. Bass has pitched in parts of the past three Major League seasons, all with San Diego, and owns a career 4.08 ERA in 75 appearances, including 18 starts.
Bass owns a 3.64 ERA in 57 career appearances out of a Major League bullpen. He made his Major League debut in 2011 and posted a 2-0 record and a 1.68 ERA in 27 appearances in his rookie season. In his 113 career Minor League games (86 starts), Bass is 33-23 with a 3.48 ERA.
In addition to veteran Chad Qualls, who signed a two-year deal with an option last week, the Astros added Darin Downs and Raul Valdes to their bullpen mix this offseason.
"We're going to give [manager] Bo [Porter] a lot of options this spring to pick guys that are going to help us get outs," Luhnow said. "I think we've made a lot of progress. We're not done and we're looking at every opportunity out there."
The Astros are still in search of another offensive player, preferably a first baseman. Corey Hart, who would have been a fit in Houston, signed with the Mariners on Wednesday and was soon joined by first baseman Logan Morrison, who was traded from the Marlins. The Astros had tried to acquire Morrison as well.
"There are still some moves we may make," Porter said. "We're always looking to upgrade our roster. You look at the first base position, another bullpen arm, maybe another starter. It's areas that we would definitely look at to improve from the free-agent market to the trade market, and we'll just see what happens."