Breaking down the Pete Alonso-Orioles deal from all angles

Pete Alonso, the Mets' all-time leader in home runs, is headed to Baltimore. The man known as the Polar Bear agreed to a five-year, $155 million deal with the Orioles on Wednesday, a source told MLB.com's Mark Feinsand. The club has not confirmed the news.

Alonso, who has the third-most home runs in the Majors since his 2019 debut season (264) strengthens an O's lineup that already possesses Gunnar Henderson, Adley Rutschman, Taylor Ward, Jordan Westburg, Jackson Holliday and more.

Meanwhile, the Mets have now seen two impact players depart in free agency this week. Alonso's decision comes one day after former New York closer Edwin Díaz agreed to a three-year deal with the Dodgers, per a source.

Here is a breakdown of this move from all angles, via MLB.com experts:

Why did the Orioles make this move?
Via Orioles beat writer Jake Rill

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.

Then, this massive news came Wednesday afternoon. To sum it up in a word: Wow.

• 5 key takeaways from Polar Bear's migration to Baltimore

Alonso’s deal will mark the highest average annual value given to a first baseman. It’ll also be the second-largest financial commitment made in the history of the Orioles, who hadn’t made this type of splash since signing Chris Davis to a seven-year, $161 million deal in 2016.

But the Davis signing occurred before Elias was hired in November 2018. Early in his tenure, the O’s were hesitant to sign long-term deals as the club underwent a lengthy rebuild. In more recent offseasons, they were unsuccessful in attempts to make this type of a splash. Now, the addition of Alonso could mark a turning point in the Elias era of the Orioles. More >

What does Alonso's departure say about the Mets' vision?
Via Mets beat writer Anthony DiComo

Over the past two and a half weeks, the Mets have moved on from three of their longest tenured players: Alonso, Díaz and Brandon Nimmo, whom they traded to the Rangers in November. Those three had all been Mets since at least 2019, forming a core that later came to include Francisco Lindor and Juan Soto.

That nucleus no longer exists, and it appears obvious that the Mets at least somewhat intended for things to go this way. They never made a formal contract offer to Alonso, according to a source, because it became clear early in the process that the bidding would go to levels they weren’t comfortable approaching.

So, then, why break up this core? The most logical answer is that it had not proven successful. More >

We’ve seen three of the top free agents (Alonso, Kyle Schwarber, and Díaz) agree to deals in the last two days … who will be next?
Via senior national reporter Mark Feinsand

The guess here is either Robert Suarez (the best reliever remaining on the market) or Michael King, who is among the top starters available.

The relief market has been moving at a rapid pace this winter, with Díaz joining Devin Williams, Ryan Helsley, Raisel Iglesias, Emilio Pagán and Kyle Finnegan on the list of free-agent bullpen arms to sign new deals.

Suarez is one of the few back-end types left on the market, with Pete Fairbanks, Kenley Jansen, Tyler Rogers and Luke Weaver also on that list.

King is likely to sign a shorter-term deal than Framber Valdez, Ranger Suárez and Tatsuya Imai, making him a popular target among pitching-needy teams. More >

Diving deep
Via analyst Mike Petriello

What makes Alonso more valuable this year than he was a year ago, when he was unable to find the long-term deal that Baltimore just handed him, despite being a year younger than he is now (31)? Timing, mostly. A year ago, the signs were trending in the wrong direction, as Alonso was coming off a second straight good-not-great-for-a-defensively-limited-first-baseman season in a row, posting a 122 OPS+, which was nearly identical to his 2023 mark.

That may sound good, and for the most part it is, but a big collapse in on-base skills (.324 OBP in 2023-’24 after .348 the previous two) as well as the lack of defensive value meant that for all the gaudy homer numbers, Alonso had been worth 2.1 FanGraphs WAR in 2024, which is to say: an average player. Worse, the hard-hit rate that had once rated as excellent had fallen to merely average in 2023, before a 2024 rebound.

“And then what happened,” as the kids maybe once used to say, and the answer is: In 2025, Pete looked like Vintage Pete again. (Mostly. We’ll get back to that.) His 142 OPS+ was a huge step forward and was slightly better than his already-impressive career average (133), but the real standout here was -- and we cannot express this part enough -- A career-best hard-hit rate, by a lot, from a guy who’d already hit 34 homers in every full season of his career. Among qualified hitters, his 54.4% mark was 11th-best, and almost all of the 10 guys above him are the names – Judge, Schwarber, Ohtani – you’d expect. (And also Romy Gonzalez, somehow.)

Add “more hard-hit” to “somewhat fewer grounders” and you end up with a barrel rate that was the third-best in baseball, behind only the two men operating on a clearly different level – Judge and Ohtani – and that’s one of the more predictive Statcast metrics. Toss in a strikeout rate that actually improved a little, and you have the perfect recipe for a walk year bonanza.

It wasn’t all roses; Alonso was incredible in four months (OPS over .900 in April, June, August, and September) while being nearly unplayable in two others (May and particularly July, when he had a .141/.242/.306 mark), and again he rated as tied for the weakest defensive first baseman. But if 2024’s performance made you wonder if you’d already seen the best of Alonso, hence the tepid interest, 2025’s underlying metrics made it clear that the Polar Bear is still in there. If he keeps up that kind of hitting or anything like it, then the likely medium-term future of a move to DH is a lot more palatable. We can assume that’s exactly what Baltimore saw

Stat to know
Via MLB.com research staff

14.9%: Few players in baseball barrel up the baseball at a higher rate and as consistently as Alonso. Since he entered the Majors, his barrel rate has never been lower than 12.3% in any season. (The MLB average is 7.2%). A high barrel rate is a key indicator of a potent bat since barrels typically end up becoming extra-base hits. Alonso's 14.9% career barrel rate ranks 10th among all players with at least 1,000 batted balls since the start of 2019.