As the race to overpay Masahiro Tanaka heats up, teams need to take into account two very important factors: 1) the Yankees really want this guy, and 2) if the Yankees really want this guy his best days are probably behind him and he's almost certainly going to underperform.
In fact, the best way to measure a player's future performance is in inverse relation to the Yankees's interest in the player. Are the Yankees making a push? Bidding against themselves and pinning the team's future on this player? Run, don't walk, away. Far away. Get a job in a league in another country if you have to, just to stay away.
Are the Yankees showing complete and utter disinterest? Go in. Hard. Remember when the Yanks wouldn't even call Ibanez after he was the only player who showed up to the 2012 postseason? He hit 29 home runs in 2013 for someone else. Remember the players the Yanks signed to replace him? Maybe, but you remember them from previous years when they were performing for other franchises.