Nick Castellanos’ deal with the Reds took the final impact free agent off the board this week. A number of quality free agents remain available -- Yasiel Puig, Brock Holt and Pedro Strop, for example -- but the baseball world’s attention now turns toward a trade market that has yet to fully develop.

The Pirates dealt Starling Marte to the D-backs Monday, the first of what could be a number of significant trades between now and Spring Training. With former MVP winners Mookie Betts and Kris Bryant along with perennial All-Star Nolan Arenado seemingly on the block, more franchise-altering moves remain in play.

What’s next as the hot stove begins to burn out? Here are some potential moves that could still be on tap before pitchers and catchers report next month.

1) Betts gets traded

Why it might happen: The Red Sox have made no secret of their desire to trim their hefty payroll, which currently sits in the $235 million range. The goal is to get beneath the $208 million Competitive Balance Tax threshold, and while trading Betts and his $27 million salary likely won’t be quite enough to get there, it would give Boston a realistic chance to accomplish that objective. A number of teams might view Betts as the final piece to push them to the next level, making him an appealing trade target.

Why it won’t: Betts is headed for free agency after the season, so the chances of him signing a long-term deal with a team that acquires him appears somewhere between slim and none. Would a team really fork over a package of players and/or prospects for one year of Betts?

Potential fits: The Padres have been the most aggressive team of late, as multiple reports indicate that San Diego is willing to send an outfielder (Manuel Margot or Josh Naylor), a pitcher (Cal Quantrill or Joey Lucchesi) and a prospect or two to Boston in a deal. The hitch? The Padres also want the Red Sox to take Wil Myers, who is owed $61 million over the next three years, though San Diego would surely need to include some cash to cover part of that contract. The Dodgers also remain in the mix as a potential landing spot for Betts.

Likelihood: Chaim Bloom, the Red Sox's new chief baseball officer, is in a tricky spot. It appears clear that Betts won’t sign an extension prior to reaching free agency, leaving the club with a tough choice to make: deal him now, wait until July (when the club could be in contention) or play out the year and receive just Draft-pick compensation if Betts signs elsewhere. It feels like a matter of when, not if, the superstar gets traded.

2) Bryant gets traded

Why it might happen: The Cubs have had a quiet offseason, with the signing of outfielder Steven Souza Jr. and an impending deal for reliever Jeremy Jeffress marking the club’s lone big league free-agent additions. Now that Bryant has reportedly lost his service-time grievance against the Cubs, potential suitors know he’s under control through the end of 2021, making him more appealing to trade candidates. Theo Epstein has been open to the idea of moving just about any of his players this offseason, and while no moves have been made, virtually nothing would be surprising at this point, even a trade of the former NL Rookie of the Year (2015) and MVP (2016)

Why it won’t: Dealing a franchise player such as Bryant is always a difficult decision, so it will likely take a prime package of players and/or prospects to pry him away from Chicago. Epstein recently said the likeliest result of the offseason Bryant saga is “status quo,” which would mean the Cubs opening the season with him om the roster.

Potential fits: The Braves seem like the obvious fit, having lost Josh Donaldson in free agency. Atlanta did add Marcell Ozuna on a one-year, $18 million deal, leaving Austin Riley and Johan Camargo to fill the void at third base. GM Alex Anthopoulos has a treasure trove of prospects from which to choose if he decides to make a big move for Bryant. Arizona has also been mentioned often as a potential suitor for Bryant, though it’s unclear whether the trade for Marte will remove the D-backs from that mix.

Likelihood: Whether Chicago will feel pressure to get something done prior to Spring Training remains to be seen, but this could easily turn into a July situation. The Cubs could also opt to trade another of their young stars instead -- Willson Contreras, perhaps? -- if they’re intent on making a big move.

3) Arenado gets traded

Why it might happen: After a winter filled with trade rumors, the relationship between Arenado and the Rockies has soured in recent weeks. The third baseman said he felt “disrespect” from the club, seemingly referring to Colorado’s lack of moves this winter following a 71-win season. Arenado’s apparent discontent with the club might force GM Jeff Bridich to reengage with teams interested in the All-Star.

Why it won’t: Having earned NL Wild Card berths in 2017 and ’18, the Rockies have hopes of a bounce-back season in '20. Trading Arenado would make the Rockies a weaker club offensively and defensively, not to mention the impact it might have on the fan base, which could feel alienated only one year after it celebrated Arenado’s long-term extension. There’s also the matter of Arenado’s opt-out clause, which allows him to become a free agent after the '21 season. That might scare off potential bidders from making an offer the Rockies would find suitable.

Potential fits: For all the same reasons that make Atlanta a logical candidate to acquire Bryant, the same can be said for the Braves and Arenado. The Cardinals might also make sense, especially if St. Louis is willing to include third-base prospect Nolan Gorman and one or two of its top pitching prospects, though the Cards might require the Rockies to take back either Matt Carpenter or Dexter Fowler to help offset some of Arenado’s contract.

Likelihood: Arenado’s exit from Colorado feels like fait accompli, but will that happen before Spring Training, later this summer or even next offseason? As long as Arenado remains with the club, this cloud will hang over the Rockies’ heads, making a quicker resolution a logical ending.

4) The Cardinals add a big bat

Why it might happen: Having parted ways with Ozuna and José Martínez this offseason, the Cardinals are still in need of at least one impact bat to hit behind Paul Goldschmidt. St. Louis could move No. 2 prospect Nolan Gorman in a deal for a proven third baseman such as Arenado or Bryant, though it would surely take a package that included other prospects.

Why it won’t: Chairman and CEO Bill DeWitt Jr. was recently on the record saying he didn’t expect a “significant” acquisition prior to Spring Training. St. Louis seems intent on replacing Ozuna’s production with a mix of young outfielders (Lane Thomas, Tyler O’Neill, Justin Williams, Austin Dean, Dylan Carlson), while the club also expects bounce-back years from the likes of Goldschmidt, Carpenter and Fowler.

Potential fits: Ozuna and Castellanos seemed like natural fits, but neither wound up with the Cardinals. St. Louis has been interested in adding a left-handed bat; could the versatile Brock Holt be a fit? He isn’t the impact hitter the club wants to acquire, but he’s a useful player, especially in the NL.

Likelihood: A major acquisition before Spring Training seems unlikely, though the Cardinals could bring in another player or two in an effort to add depth. A trade for Arenado or Bryant would be the best course to acquire an impact player, though given DeWitt’s assertion that the payroll isn’t going to increase much, St. Louis would likely need to shed the contract of either Carpenter or Fowler to make such a deal happen.

5) The Rangers add offensive depth

Why it might happen: GM Jon Daniels still wants to add another bat, preferably a right-handed one. Danny Santana is slated to play center field, but Texas likes the idea of using him as a utility player, while first baseman Ronald Guzmán is a lefty hitter who has yet to produce at the big league level. Adding a platoon partner at first base would seem to be in the cards.

Why it won’t: As we mentioned, the free-agent market isn’t exactly teeming with big bats. To add players at first base and/or center field, Texas will be looking to hit big on a lottery-ticket type of free agent.

Potential fits: Mark Reynolds and Steve Pearce are among the few righty-hitting first basemen on the free-agent market, though the Rangers could give Sam Travis (whom they acquired from the Red Sox earlier this month) a shot to win a job. Kevin Pillar and Billy Hamilton are the best of the remaining free-agent center fielders, though the Red Sox's Jackie Bradley Jr. and the Reds' Nick Senzel might be options if their current clubs decide to move them.

Likelihood: Texas will almost certainly make another move or two in order to add depth at first base and in center field, though nothing in the same realm as its trade for Corey Kluber, which will undoubtedly be its biggest move of the winter.