The New York Mets snapped a streak of six straight losing seasons in 2015 and won their first pennant in 15 years. The success should be sustainable too, considering the Amazin's are well-armed for the future with Matt Harvey, Jacob deGrom, Noah Syndergaard and Steven Matz -- and with Zack Wheeler poised to return from Tommy John surgery in June or July.

Still, the Mets must try to offset the expected departures of free agents Yoenis Cespedes and Daniel Murphy. Will a full season of Michael Conforto plus healthier 2016 campaigns from David Wright and Travis d'Arnaud be enough? Perhaps not.

That's why the offseason will be so important.

Here's a primer of 10 things to monitor this winter:

1. The qualifying offer: The Mets will learn by Friday at 5 p.m. ET whether Murphy will accept a one-year, $15.8 million qualifying offer. Murphy is expected to decline. The Los Angeles Dodgers may be among his potential suitors. If Murphy happens to accept, a large portion of the Mets' offseason spending capability will go his way.

2. Yo no: Cespedes recently indicated to ESPN Deportes' Marly Rivera that he wants at least a six-year deal. With that in mind, he is highly likely to end up elsewhere. Mets officials remind themselves that Cespedes' torrid two-month regular-season performance with the club is not reflective of his body of work over full four years in the majors. Plus, general manager Sandy Alderson does not plan to give a six-year deal to a player who already has reached 30 years of age.

3. Center of attention: Curtis Granderson and Conforto should have full-time roles in the outfield corners in 2016, which leaves righty-hitting Michael Cuddyer trying to scrounge up playing time against left-handers between left and right field, plus at first base for Lucas Duda. The Mets need a complement for righty-hitting Juan Lagares who can man center field. Denard Span and Dexter Fowler would be the high-end options, with Gerardo Parra, Will Venable and David Murphy also on the free-agent market. Colby Rasmus will be off the table. He reportedly is poised to accept a qualifying offer and return to the Houston Astros. Trade-wise, perhaps the Mets match up with the Boston Red Sox for Jackie Bradley Jr. or Arizona Diamondbacks for Ender Inciarte.

4. Shortcomings: The Mets maintain they are confident with a middle-infield combination of Wilmer Flores, Dilson Herrera and Ruben Tejada in 2016, although Tejada reportedly is a non-tender candidate because he might make about $2.5 million. While the priority is the outfield for now, the Mets did discuss Andrelton Simmons with the Braves as recently as Thursday morning at the GM meetings, before he was dealt to the Angels. The likelihood is that the Mets stay internal at shortstop, reasoning that the current group helped them get to the World Series.

5. Don't touch: You can never say never, but assistant GM John Ricco indicated that he told teams this week it is very unlikely the Mets would be willing to part with Harvey, deGrom, Syndergaard or Matz in a trade. Wheeler is not quite in that category, but the Mets expect to retain him as well.

6. Winter watch: Twice-suspended Jenrry Mejia is pitching in winter ball and the Mets are keeping tabs. The Mets feel betrayed by Mejia's pair of 2015 performance-enhancing-drug suspensions and could non-tender him at the Dec. 2 deadline. Otherwise, Mejia would receive a prorated portion of his 2016 salary after returning from suspension in July. His base salary for the year would have to be at least 80 percent of the $2.595 million that he was due to earn this past season before the suspensions.

7. GM watch: Alderson fainted last week at Citi Field after the formal portion of a press conference to announce a two-year contract for Terry Collins, which will keep the manager in the dugout through 2017. Alderson did not attend the GM meetings, because he was supposed to undergo an undisclosed medical procedure, according to Ricco. However, Alderson was in contact with Mets executives throughout the week though, Ricco said.

8. Payroll watch: Alderson hopes the payroll opens 2016 exceeding the roughly $103 million at which it opened this past season. Considering the Mets already have roughly $92 million committed to salaries for next season (including salary projections for arbitration-eligible players who are expected to be tendered), let's just say don't expect a winter spending spree.

9. Bench mark: If Murphy departs and Herrera is the second baseman, the Mets still need a backup infielder. If it's not Kelly Johnson returning, it should be someone of that ilk. The Mets undoubtedly have interest in Ben Zobrist, but aggressive bidding is expected to take his price tag beyond the Mets' appetite.

10. Setting the table: The Mets plan to tender Addison Reed as one primary setup man to Jeurys Familia, but they still need another. Joakim Soria and Darren O'Day are expected to get closer-type money and be beyond the Mets' reach. Perhaps a lefty such as Tony Sipp makes sense. Reed, by the way, might earn roughly $5.5 million in 2016 before becoming eligible for free agency. While left-hander Josh Edgin may be ready for Opening Day after rehabbing from Tommy John surgery, the Mets likely will bring in a lefty option as a hedge. They also have Josh Smoker and Dario Alvarez internally.