Ed Wade signed Wandy Rodriguez to a strange contract back in January 2011. Wandy received a three-year deal worth $34m from 2011-13 ($7m in 2011, $10m in 2012, $13m in 2013) pushed higher by a signing bonus and buyout for 2014. However, there was a clause in the contract that gave Wandy a $13m player option for 2014 if he was traded at any point during the contract which, of course, he was.
So today Wandy exercised that 2014 option, and under the terms of the trade with Pittsburgh, the Astros will be picking up $5.5m of the $13m owed Wandy in 2014.