The Mets had a truly historic offseason when it comes to spending to strengthen their roster, bringing in external free agents like Justin Verlander, Kodai Senga, David Robertson, and Jose Quintana.

New York also retained a bunch of key internal free agents, including Edwin Diaz and Brandon Nimmo.

Add it all up, and you get a team that has gotten its heavy lifting out of the way as it decides on the 26-man roster for Opening Day.

When it comes to the regular starting lineup and who will play where, most of that is set.

The starting five in the rotation -- barring injury or something very strange happening -- is cemented.

As far as the bullpen, there are already five locks.

Still, there are plenty of big storylines to watch at spring training.

Here are the top five...

What's the plan for Francisco Alvarez?

The Mets aren't necessarily divulging the plan for their top prospect, but if you parse GM Billy Eppler's words, you can get a sense of what their thinking is.

Eppler has said that Alvarez will not be a candidate for the full-time DH job. That's because the Mets view Alvarez as a catcher, and having him in the majors as a full-time DH would stunt his progress when it comes to refining his defense behind the plate. It would also prevent him from learning how to manage a big league staff.

While you can cross Alvarez off the list as a full-time DH candidate (and the Mets are right to be refusing to entertain that role for the 21-year-old), what can't be ruled out is Alvarez being in the bigs this season in a hybrid catching/DH role.

If the Mets believe by Opening Day that Alvarez's bat is ready and that his defense is passable, having him split the full-time catching duties with Omar Narvaez while getting DH at-bats when he's not behind the plate would make lots of sense -- especially with the Mets still in need of a power bat.

Additionally, even once Alvarez is established in the majors, it will still be wise to DH him plenty. There's no reason to run his body into the ground by having him catch most days.

Can Brett Baty win the third base job?

I argued recently that the Mets should give Baty the opportunity to be the long end of a third base platoon with Eduardo Escobar, with the ability for Baty to grow into the full-time role this season.

And in Keith Law of The Athletic's recent Top 100 prospects list, he said the Mets should give Baty "500 at-bats this year" in the majors, opining that "there's nothing left for him to learn in the minors."

Baty is 23 years old, was not overmatched during his brief taste of the majors last season, and displayed a good plan at the plate.

Combine the above with the fact that the switch-hitting Escobar is much better against lefties than righties, and it's clear that Baty should get a serious shot to make the roster.

How will the DH situation shake out?

The DH role could be impacted by whether the Mets carry Baty from the jump and play him at third base against most right-handers. If they do, it would open up plenty of DH at-bats for Escobar. Carrying Alvarez would also impact the DH situation, since he would likely be getting a bunch of at-bats there when he's not catching.

If the Mets start Baty and Alvarez in the minors, their main DH options will be Daniel Vogelbach (against right-handers), and Tommy Pham/Darin Ruf (against left-handers).

With Vogelbach, Ruf, and Pham, the Mets have three players who are basically all-hit, no-glove. It would be odd to have both Pham and Ruf on the roster, since it would severely limit the ability of Buck Showalter to maneuver during games.

So it seems that something will have to give here -- potentially a trade of Ruf.

Who will fill out the bullpen?

Diaz, Robertson, Adam Ottavino, Brooks Raley, and Drew Smith are locks. And there's a chance that John Curtiss, whom the Mets signed to a two-year deal last offseason as he rehabbed from Tommy John surgery, will have an inside track at one of the other spots. He does have minor league options remaining, though.

If the above six pitchers are in the bullpen, the Mets have room for one or two more, depending on if they carry seven or eight relievers.

Bryce Montes de Oca, who has otherworldly stuff but needs to refine it, has a chance, as do David Peterson and Tylor Megill (more on them below).

The Mets also have plenty of other bullpen options, including Stephen Ridings, Rule 5 pick Zach Greene, and Jeff Brigham.

How will David Peterson and Tylor Megill be utilized?

With the starting rotation set, the Mets will have to decide what the best roles for Peterson and Megill are.

Both are starting pitchers who spent part of last season in the bullpen, and it would make sense for the Mets to keep one of them stretched out at Triple-A Syracuse.

That could mean having Peterson on the big league club as the long reliever/second lefty in the pen/spot starter, while having Megill working as a starter at Syracuse.

Either way, the Mets should have two solid rotation options ready to step in if a need arises -- and it always does.