Under the terms of Ryan Howard's five-year, $125 million contract with the Philadelphia Phillies, he can block trades to 20 teams.

That leaves only nine clubs where Howard can be traded without his permission.

The limited no-trade clause makes exploring a trade involving Howard difficult for the Philadelphia front office.

According to a source, the nine teams Howard can't block a trade to are: the Detroit Tigers, Kansas City Royals, Los Angeles Angels, Seattle Mariners, New York Yankees, Texas Rangers, Tampa Bay Rays, Baltimore Orioles and Boston Red Sox.

Howard will earn $25 million in both 2015 and 2016. The Phillies have a $23 million club option for 2017 with a $10 million buyout, so Howard is guaranteed a minimum of $60 million through the end of his contract.