Geez, it's only mid-December, a handful of free agents have signed, and the Phillies have to wait because agents always shoot for the moon, then when they don't get what they asked for, start serious negotiations.
So if they want to sign someone like Sanders, first they have to wait for him to find out if anyone will give a 3-4 year deal at reasonable money, if not, then he'll listen to 1-2 year offers. So they have to be patient, let the upper tier FAs sign, then once landing spots have evaporated the kind of patches they're looking for will be willing to listen to offers.
Move fast on the guys you really want and are willing to pay, move slow on the guys you don't want to overpay.