There's something to be said for buying low on a bounce-back free agent versus buying high on a guy coming off a career year. They clearly value Garcia's somewhat better power (hard-hit balls, exit velocity) over Bader's possibly unsustainable bat speed and BABIP, and the defense is the same. Garcia might be able to be a middle-of-the-order bat again. Bader is not going to turn into one.
It's also a commitment to Crawford.
One assumes Garcia had other offers that prompted the Phillies to snap him up so quickly, even as they are still carrying Nick's contract. And at the end of the day, for all the talk about how they'd love to have Bader back, they didn't really want him back. They can read his baseball card and remember the slumps and injury he had even amidst his magic short-term contribution.