If a team offers a qualifying offer to a free agent, the free agent can accept the offer and automatically agree to a 1yr/$14.1m deal. If they don't accept said offer, they hit the market but the former team receives a draft pick.
In the Astros' case, if they sign a free agent who has rejected a qualifying offer they do not lose the 1-1 pick. They do, however, lose the 1-40 pick - Round A Competitive Balance pick they acquired from Baltimore in the Bud Norris trade (along with L.J. Hoes and Josh Hader).
So the question is if the Astros are willing to give up that pick, or did they push for that Competitive Balance pick from Baltimore in order to have the flexibility to give it up by signing a higher-profile free agent? If you ask this question, you should know full well that Jeff Luhnow and the Decision Sciences department have already killed you.
Who are the notable free agents who have been offered a Qualifying Offer?
Ubaldo Jimenez, as well as (via MLBTR): Carlos Beltran, Robinson Cano, Shin-Soo Choo, Nelson Cruz, Stephen Drew, Jacoby Ellsbury, Curtis Granderson, Hiroki Kuroda, Brian McCann, Kendrys Morales, Mike Napoli, Ervin Santana.
Obviously the Astros aren't in the market for all of them, but maybe this changes your opinion of signing someone like Nelson Cruz or Shin-Soo Choo.