If you were not up late on Sunday night, you might have missed that the Philadelphia Phillies and Seattle Mariners had agreed in principle on a trade that will send shortstop Jean Segura to the Phillies.  Early on, we knew that shortstop J.P. Crawford might be headed to Seattle in such a deal.  But the trade, which could be announced on Monday, is starting to take shape.

Ryan Divish of the Seattle Times reported that first baseman Carlos Santana would be included in the deal:

Major League Baseball sources confirmed Sunday evening that the Mariners were working toward finishing a trade that would send All-Star shortstop Jean Segura and possibly one other player to the Philadelphia Phillies in exchange for a package of players including first baseman Carlos Santana and shortstop J.P. Crawford.

What other players might be included remains to be seen.

First, it is clear the Phillies would likely send some sort of prospect or prospects to Seattle.  While Crawford has some sort of upside, that the Mariners are taking on Santana probably means that the Phillies need to sweeten the pot, should the Mariners keep Santana.  However, they may not.

The Mariners might flip Santana, Divish noted on Twitter.  We learned last week that the Colorado Rockies had interest in Santana.  They could make another trade with the Mariners after this deal is complete.

Also, keep an eye on the Seattle Mariners roster. I would not be shocked if another salary is attached to the deal.  Santana is set to earn about $2.4 more than Segura will this year and next year.  There might be other money coming back to the Phillies, with Seattle in rebuild mode and looking to unload contracts.

Keep an eye on reliever Juan Nicasio.  Nicasio, you may remember, was a Phillie for about a week in 2017.  The Phillies claimed Nicasio from the Pittsburgh Pirates on August 31, 2017.  Then, the Phillies traded Nicasio to the St. Louis Cardinals on September 6.

The Cardinals successfully used Nicasio as a closer down the stretch before he hit free agency.  The Mariners signed Nicasio to a two-year, $17 million deal prior to the 2018 season.  Nicasio did not repeat the success of 2017.

Nicasio was 1-6 with a 6.00 earned run average for the Mariners in 46 games before having season-ending surgery in August.  Earlier in the season, Mariners manager Scott Servais called Nicasio "unlucky" in response to his performance.  $9 million is due to Nicasio in 2018.

UPDATE, 10:51 a.m.: Bob Nightengale of USA Today believed that the same type of concept I suggested was taking place, but says the name is Anthony Swarzak, recently shipped from New York to Seattle.  However, Jayson Stark of the Athletic believes it is NOT Swarzak, but another similar type of deal.  Stay tuned.

We will know the full details soon.  If there is money changing hands in addition to contracts, the clubs will need commissioner approval.  The Mariners and Mets completed a trade of second baseman Robinson Cano and closer Edwin Diaz last night, so this could be the next order of business.

Chances are the deal will help both teams.  Phillies general manager Matt Klentak was assistant general manager to Seattle general manager Jerry Dipoto for the Los Angeles Angels of Anaheim before Klentak joined the Phillies.