PHOENIX -- The 2017 season was a pleasant surprise for D-backs fans, who got a chance to see their team play in the postseason for the first time since 2011.
Expectations were low for Arizona coming off a disappointing 2016 season (69-93), but the D-backs will not be able to sneak up on the rest of the National League in '18, nor will they be able to escape increased expectations.
The D-backs return most of last year's team, and general manager Mike Hazen has spent the offseason trying to add to the roster without going over what already projects to be a D-backs record budget of around $115 million.
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As the calendar flips to 2018, here are five of the biggest questions the D-backs face:
1. How do they replace Martinez?
The D-backs have stayed in touch with J.D. Martinez, but it's still hard to figure how the outfielder's price tag can fit within the team's payroll going forward. Assuming he doesn't return, the team will need to find a way to at least replace some of the offense he brought.
Yasmany Tomas is expected to be recovered from the injuries that limited him last year, so he is one piece of that puzzle. But the D-backs don't have a lot of depth in the outfield, so that's an area they will need to shore up.
It's also worth noting that the D-backs were a good team (13 games above .500) last year even before they acquired Martinez.

 2. Is Zack back?
The D-backs talked with several teams at the Winter Meetings about deals involving ace Zack Greinke. Trading the right-hander would free up quite a bit of money, which could allow them to address other needs, but at the same time, it would take away their ace.
Even overlooking Greinke's 17 wins, which are devalued in today's analytics-heavy game, Greinke was a key piece of the rotation, tossing 202 1/3 innings and ranking third among National League pitchers in WAR with a 5.3 mark.
If the D-backs do deal Greinke, which doesn't seem likely, they will need to figure out a way to replace him with another front-end starter.

3. Is Archie Bradley ready to be the closer?
The D-backs had interest in bringing back last year's closer, Fernando Rodney, but he signed with the Twins.
Bradley seems like a natural to take over that role given the success he had as a setup man last year, when he posted a 1.73 ERA, a franchise record for a reliever. Bradley's stuff played up -- he hit 100 mph at times on the stadium's radar gun -- and it reduced his need for a pitch other than his fastball and curve.
As team's have found in the past, though, there can be a big difference between pitching in a setup role and being a closer. Bradley seems to have the right makeup for the role, but the only way to know for sure is to give him the chance to do it.

4. Who's up the middle?
The D-backs have a surplus of middle infielders with Chris Owings, Brandon Drury, Nick Ahmed, Ketel Marte and Daniel Descalso. Carrying all of them on a 25-man roster could be tough, even if they decide to use Owings as a jack of all trades and play him some in the outfield.
The depth at the position came in handy last year when Owings and Ahmed were both lost to season-ending injuries, but it makes sense at this point for the team to deal from this surplus to fill other pressing needs.

5. What will the catcher rotation look like?
The D-backs experienced a sharp turnaround in the performance of their pitchers from 2016 to '17, and one of the reasons Hazen cited was the emphasis the organization put on having defense-first catchers.
Jeff Mathis, Chris Iannetta and Chris Herrmann rotated last year, but with Iannetta lost via free agency to the Rockies, the D-backs are left with just Mathis, Herrmann and John Ryan Murphy as catchers on the 40-man roster.
"We want the catchers to take care of the pitchers first and foremost and run the game and make sure we're pitching night in and night out," Hazen said. "We feel that's the best path to success. We would be comfortable going into the season with the catching configuration we have. We're not tied to two or three catchers, but I do think the three-catcher system worked out pretty well for us."