A quick rundown before we get down into it. The Houston Astros can lose up to three pitchers from their starting rotation last year. Lance McCullers had Tommy John surgery a few weeks ago, Dallas Keuchel rejected his qualifying offer and became an unrestricted free agent, and Charlie Morton is an unrestricted free agent, though the Astros have made an offer to retain him.
So, that is exactly a 500 inning void the Astros currently have to fill this offseason. The team has been endlessly linked to nearly every pitcher available, both in the free agent market and on the trade block.