Of course, because, why not? He'll likely spend the next two to three weeks getting starts in the minors à la Andy Pettitte did before joining the Rangers around mid-June if it all works out. So the Mariners opportunity to beat up on Scott Feldman is limited. Better act now, Mariners! Like, very nearly right now when you have a game against him in a couple hours.
The deal is purportedly going to cost the Rangers a pro-rated amount of about $5 million. Roy Oswalt is probably worth quite a bit more than about that in terms of production value if he's able to stay on the mound.