Signing one bad contract can sink an MLB franchise, and there are plenty of those deals floating around the big leagues right now. Teams overpay for free agents every year, brazenly dropping nine figures to bring players to their organizations in hopes that their aggressive moves on the open market can yield postseason success and maybe even a World Series title. But when boldness backfires, often in the form of a long-term contract at vastly too high a rate, it can hamstring a franchise for years.  Currently, there are several long-term contracts that have already aged poorly or look likely to go down that path in the coming years. We’re going to examine the 10 worst MLB contracts currently on the books. 10.…