After signing a huge deal with the Orioles, Pete Alonso made some unique baseball history in the process for a first baseman.

The Orioles wanted to be aggressive this offseason. President of baseball operations Mike Elias was expressing a willingness to spend more money than at any point before. And it felt like a big move was brewing all week at the Winter Meetings.

BREAKING: First baseman Pete Alonso and the Baltimore Orioles are finalizing a five-year, $155 million contract, sources tell ESPN. Alonso leaves the Mets to make a loaded AL East even better. Alonso becomes the second Mets’ star to leave in as many days after Edwin Díaz inked a three-year, $69 million pact with the Dodgers on Tuesday evening.

A person with knowledge of the agreement says the Baltimore Orioles have agreed to a $155 million, five-year deal with slugger Pete Alonso.

Take a look at Pete Alonso's five career home runs at Camden Yards after reportedly signing a five-year deal with the Orioles

The signing gave the Orioles a slugger that they have long coveted, while also taking a target off the board for their rivals in the AL East, the Boston Red Sox. Alonso’s departure also stands as the latest domino to fall in a transformational offseason for the New York Mets, who have lost several mainstays in their clubhouse.

All winter, slugger Pete Alonso seemed like a perfect fit to join the Red Sox lineup. Instead, he’s joining a motivated American League East rival on a big contract.

Good news, everybody, the Red Sox are totally in on Ketel Marte! Except maybe they’re not: The Sox have also checked in with the Diamondbacks — a team in need of rotation help — about the availability of star second baseman Ketel Marte,