The New York Yankees got one of the big trade pieces of the offseason. James Paxton was one of the two big pitching names (Cleveland's Corey Kluber) and Brian Cashman made it a point to get him. The team gave up their number one overall prospect in Justus Sheffield as the main piece going back to Seattle.
Anytime you have to give up your top prospect the return will need to be better. James Paxton is 30 years old (not ideal) however he is under team control for the next two years (very much ideal). This means that the tall lefty will be under team control for his "prime seasons". Sheffield on the other hand just hasn't reached the level the Yankees wanted him to reach by this time. The best time to trade him was right now or hope he panned out. Erik Swanson and Dom Thompson-Williams were also part of the deal. Thompson-Williams was more or less the add into the deal and Swanson could have been lost for nothing in the rule five draft this offseason.
Cashman is focused on bringing in a championship and will focus on pitching to make that happen this offseason.