The Russell Martin contract was one of the best things Alex Anthopoulos did in his time here. He's provided 8.6 fWAR so far on his $82.5M contract, and will probably finish the deal at about 10 fWAR. That, on it's own, would be fine given that in his two most productive seasons the wins he provided helped the team get to the playoffs.
But his value goes beyond the fWARs. He's provided wins via framing, and the unquantifiable stuff has value too: he's been a steady, consistent presence behind the plate and in the clubhouse, and by all accounts pitchers love throwing to him.
This is the kind of expensive free agent splash that serious teams with big payrolls can make once in awhile and really set themselves apart from the Tampa Bays and Oaklands of the world.