Historically, finding a big-name catcher in the free agent market has been a difficult task. With catchers generally getting full-time jobs at older ages -- and aging worse than players at other positions -- snagging a star backstop in his prime is a difficult task. When a team has one of the best catchers in the league, they've generally placed a priority on keeping their catcher. Johnny Bench was never a free agent, Mike Piazza and Gary Carter weren't up for bidding until well after their primes, and even Ivan Rodriguez and Carlton Fisk, two of the most prominent free agent catchers of the last 35 years, were available only for top dollar at risky ages. Given Minnesota's miserly ways, teams salivated for years at the prospect of getting the opportunity to land a 27-year-old Joe Mauer, but even the Twins saw what they had and gave their former No. 1 pick one of the richest contracts in history.
I've ranked the best catchers in the FA market by their three-year wins above replacement (WAR) in a neutral park as projected by ZiPS.