The Mariners weren't hearing it. They suspended Mateo for 10 games for missing the game without permission and then promptly optioned him out to AAA Tacoma where he has stayed for over two months without even a hint of returning to the majors. Even though he was putting up dominating numbers and the Mariners were doing everything in their power to stay in the AL West race, they didn't relent.
In the end, the Mariners disposed of Mateo by sending him to Philly for infielder Jesus Merchan.
In all honesty, Merchan, who is 26, isn't a great prospect and the Phillies had no trouble with giving him up. He's a nice player, but most scouts agree that his potential is limited and he might be able to serve as a utility player at the Major League level, but that's best case scenario.
The Phillies look at Mateo as insurance for their bullpen, but it's likely that they would also look at him for a September call-up if not for a pesky trial date scheduled for September 4th. What role he'll play with the organization, if any, remains to be seen and considering they gave up next to nothing, the move won't hurt their organization from a player standpoint. It may hurt from an attitude standpoint among some players who will look at Mateo as a pariah and you have to hope that it won't provide the wrong influence for young players coming up through the system, especially since he has to play with younger players at the AA level thanks to his travel limitations.
Perhaps this is a move where the Phillies should have taken a higher road, much like the one the Mariners took, and left this guy to rot in somebody else's organization. There is always the chance that the charges are false, but come on, there should be little dispute about whether his wife showed the physical signs of abuse and if it was just the two of them - and their four year old son - in that hotel room, Julio Mateo is going to have a hard time explaining all of that away.