The New York Yankees have struck the first major trade of baseball’s offseason, acquiring Seattle Mariners ace lefty James Paxton in a deal that will solidify the front of their rotation while sending three-prospects to the rebuilding Mariners.

The Yankees and Mariners made it official Monday afternoon, but Yahoo Sports’ Jeff Passan was first to report the deal was agreed upon:

The Yankees are sending three prospects to Seattle in return, including left-handed pitcher Justus Sheffield, who is New York’s No. 1 prospect, according to MLB.com. Right-handed pitcher Erik Swanson and outfielder Dom Thompson-Williams are also going to Seattle.

The deal makes it official: The Mariners are rebuilding this offseason. Even though they won 89 games last year, the Mariners front office was reportedly thinking about trading away their most valuable assets to rebuild their farm system, convinced they couldn’t compete in the AL West with the likes of the Houston Astros. Consider that confirmed.

Paxton, 30, was viewed as one of Seattle’s more desirable players. The last two seasons he’s turned into a top-of-the-rotation starter for the Mariners. Last year, he was 11-6 with a 3.76 ERA and a no-hitter to his credit. In 2017, he was 12-5 with a 2.98 ERA. When he’s on, Paxton is also a strike-out machine. He had eight games last season in which he registered double-digit strikeouts, including a May game against the A’s in which he struck out 16 batters.

Health has always been the thing holding Paxton back, and indeed his inning count the past two years left something to be desired: 160.1 in 2018 and 136 in 2017. Still, the Yankees just need Paxton to be a solid No. 2 with Luis Severino as their ace. With Masahiro Tanaka behind Paxton, the Yankees’ frontline is already much improved.

A plus with Paxton is that he’s under team control until 2021. Salary arbitration should make him a relative bargain for the big-spending Yankees. He earned just $4.9 million in 2018.

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