As you mentioned, very few players in their primes (under 30)hit free agency. Look at high profile free agents: Zito, Fielder, Pujols, etc. Albatross contracts that hamstring an organization. I'm sure there are some that work out. Greg Maddux comes to mind, but he was 27 and the and the Cubs had issues, and arguably that was a different era. Big money contracts are rarely worth it, especially for those that get themselves in the position to reap the rewards. Age, satisfaction, many factors contribute. Adding a sensible free-agent to address a weakness in a mature team? Hell yeah. Chili Davis, Jack Morris, good adds that helped put their team over the top, all low risk short term deals. Big money free-agency is a fool's game.