Liriano, who will join the team Tuesday, will pitch out of the bullpen, manager A.J. Hinch said.
"We tried to get a lot done today," general manager Jeff Luhnow said. "We were working on several different things. Acquiring a pitcher like Liriano was a priority for us. Not only has he been a starter, he's been a reliever, he's got postseason experience. We really think he can help this club out in an area of great need."
Luhnow admitted there was disappointment in not being able pull off an impact deal, but said it wasn't for lack of effort. He said early in the trading season, the cost was "extremely high" on all players, but it did come down a little bit in certain areas to the point they thought they had some deals done.
"We had some we were close to almost over the finish line," he said. "At times, I would have put them at 90-percent-plus that we would have got them done. There's a lot of dynamics that happen with these deals, and for reasons I can't really talk about, they didn't happen. I do believe this team has what it takes to win the postseason with the players we have."
Ultimately, part of the reason the Astros weren't able to make a splash at the Trade Deadline was their unwillingness to deal prospects like outfielders Kyle Tucker (ranked by MLBPipeline.com as the Astros' No. 1 prospect) and Derek Fisher (No. 4), who will get more playing time with Aoki gone.
"We were in a lot of the players that moved, but our bundle of moves or our headline player, or whatever it was, wasn't quite up to snuff with the alternatives we have," Luhnow said. "That's something we can't control."
Not many players were available for comment in the clubhouse Monday, but pitcher Lance McCullers Jr. and veteran outfielder Carlos Beltran both said the Astros are good enough to win as currently constructed.
"Of course, you see the guys you maybe are competing against deep in the playoffs and then the World Series and they're going out and getting big names," McCullers said. "I think those teams are in more of a position where they needed to do that. I think the guys we have here are capable of winning a ring for the Houston fans."
Liriano, 33, was 6-5 with a 5.88 ERA in 18 starts for the Blue Jays, but held lefties to a .226 batting average. He also has postseason experience, starting against and beating the Pirates in the 2013 National League Wild Card Game.
Hernandez, who was the Astros' ninth-ranked prospect by MLBPipeline.com, is no stranger to Astros fans. He appeared in 41 games last year, hitting a homer in his Major League debut in Toronto. He was called up this April when Jake Marisnick went on the disabled list and suffered a lower leg bruise in his first game in a collision with Jose Altuve in Cleveland. Hernandez went on the DL and had been in Triple-A Fresno, where he hit .279 with 12 homers, 44 RBIs and 12 steals.
Aoki, 35, was claimed off waivers in November and is owed nearly $2 million of his $5.5 million salary. He appeared in 71 games for the Astros this year, hitting .272 with a .323 on-base percentage.
"I've been keeping up with trade rumors and everything like that," Aoki said. "I never thought that I would be included."
Fantasy spin | Fred Zinkie (@FredZinkieMLB)
While Liriano and Aoki will stay on waivers in all mixed leagues, Fisher could be the biggest beneficiary of this deal. The No. 4 prospect in the Astros organization, according to MLB Pipeline, Fisher should get an extended opportunity to show his skills in the coming weeks. And as part of the highest-scoring lineup in baseball, the 23-year-old -- who hit .318 with 21 homers and 16 steals across 384 plate appearances in Triple-A this season -- could dent some shallow-league rosters down the stretch.
Brian McTaggart has covered the Astros since 2004, and for MLB.com since 2009. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.