Literally every single situation is different. Hawks signed Hossa to a 9.2% of the cap deal during UFA and won three cups. They signed Soupy to a deal worth 12% of the cap in 08. One worked amazing, one kinda worked. Minnesota used UFA and was a good team for a long time with Parise and Suter, just ran into the Hawks every year. Signing UFAs aren't going to flip you to be good immediately but they also can be around when you are good.