The Mets' Matt den Dekker (6) is congratulated by Lucas...

The Mets' Matt den Dekker (6) is congratulated by Lucas Duda (21) after scoring on a sacrifice fly by Daniel Murphy during the first inning of a game against the Houston Astros on Sunday, Sept. 28, 2014, in New York. Credit: AP / Rich Schultz

Lucas Duda high-fived his teammates in the dugout after his 30th trip around the bases this season. Still, the crowd demanded more, refusing to relent until the slugger offered a curtain call.

So the reluctant Duda climbed the steps and raised his helmet, providing both an exclamation point to this season and a blueprint for the next. Improvement, general manager Sandy Alderson said, will only come if the Mets can bolster what he called a "middle of the pack" offense.

"I'm very pleased with what we were able to accomplish this year," Alderson said Sunday, following the Mets' season-ending 8-3 win over the Astros. "I like what we have going forward. But at the same time, we need to get 10-12 games better and whether we can do that from within is difficult to say. We're not going to rely on what we have currently but I like what we have."

The Mets capped a year of incremental gains. Though they posted a 79-83 mark -- five games better than a year ago -- they finished tied for second and 17 games behind the Nationals.

For the sixth straight year, the Mets finished with a losing record. And for the eighth straight year, they missed the playoffs. Yet they considered this season a springboard back toward contention. "We're close," Mets captain David Wright said. "And that's a good feeling going into the offseason."

Much of that optimism stems from the pitching staff, which finished with a 3.49 ERA, sixth in the National League.

Jacob deGrom emerged as a budding ace and contender for NL Rookie of the Year and Zack Wheeler took a clear step forward in his development. Ace Matt Harvey returns next season, along with a stable of veterans such as Jonathon Niese, Dillon Gee and Bartolo Colon. Top prospect Noah Syndergaard will be waiting in the wings.

The bullpen turned into a strength. Vic Black, Jeurys Familia and Jenrry Mejia formed a dangerous triumvirate. And the Mets can gain more firepower with the expected return of Bobby Parnell following Tommy John surgery.

Now, the Mets must find a way to get more out of their bats, especially since the early signals indicate that payroll will remain at roughly $85 million.

"Certainly, the big thing is, we've got to hopefully get ourselves another bat in the middle of our lineup," manager Terry Collins said. "I think that changes a lot of things."

However, the Mets appear prepared to address their offense in other ways. Alderson said the Mets will likely bring in the fences to reduce the expanse in Citi Field's centerfield and right-centerfield.

According to a source, it's possible the club will bring in a new hitting coach this week, though Alderson declined to discuss staff changes. An announcement is expected within a few days.

Questions remain in leftfield and shortstop, though the Mets discovered a centerfielder in Juan Lagares and a catcher in Travis d'Arnaud. They must hope for bounce-back years from Wright and Curtis Granderson. And they need a command performance by Duda, whose 30 homers ranked third in the NL. Still, the Mets ranked ninth in homers (125), 13th in average (.238) and eighth in runs (629). Repeating a common theme, Alderson insisted that improvement is close.

"Do I think we can get from eight to five [in runs] with what we have? I think it's possible," he said. "But that doesn't mean we'll rely on what we have . . . I do think we need to get better in that regard, but we don't have to get a lot better."