EDEN PRAIRIE, Minn. — As tough as it might be, Vikings Head Coach Mike Zimmer wants his defense to be even better in 2018.

Minnesota ranked first in the NFL in points (15.8) and yards (275.9) allowed per game, and the unit also posted the league's top third-down rate at 25.2 percent.

The Vikings defense had one new starter in 2017 in rookie linebacker Ben Gedeon, while mainstays such as defensive end Everson Griffen, defensive tackle Linval Joseph, linebackers Anthony Barr and Eric Kendricks, cornerback Xavier Rhodes and safeties Harrison Smith and Andrew Sendejo stayed intact as key members of the unit.

Zimmer said Tuesday at his end-of-the-season press conference that he had high hopes for his defense entering the season, and that they rose to the challenge of playing well. 

"I think I knew we had a nucleus of defensive guys that had played pretty well in the past. You never really know how the season is going to unfold," Zimmer said. "I've had teams that I thought were going to be really good, and they didn't play good together. This team is a pretty special group of defensive guys that have played together for quite a while now."

But although the Vikings produced one of the top seasons in franchise history, Minnesota's season ended in bitter fashion as the defense gave up a season-high 38 points and 456 total yards of offense in a loss to the Eagles in the NFC Championship.

Zimmer said Tuesday he wants his unit, and himself, to continue to find ways to improve.

"There's some things we have to get better at. I have to do a better job in some areas as far as maybe sticking to some things too much because we're successful," Zimmer said. "One of things we planned to do, first of all, we're going to self-scout. See the things we're good at and plays that hurt us. Then, we're going to look at how we can try to take this thing to the next level."

Zimmer said it will be up to himself and the Vikings defensive coaches to find a way to enhance a defense that already ranked as the NFL's best in 2017.

"There's some things that I really want to look at this offseason," Zimmer said. "There's some other teams I want to study that have done a good job. 

"I want to go back and evaluate a lot of our rush situations to see if we can improve in some of those areas. Go back and see why we were good on third downs. Our job as coaches is to, number one, put the players in the best position possible to win," Zimmer added. "Number two, to try to continually get better, figure out new ways to do things. I think that's how you come up with new concepts, new ideas, new ways to attack offenses."

Perhaps the biggest surprise Sunday was that the Vikings historic third-down defense couldn't keep the Eagles offense from moving the chains time and time again.

Minnesota allowed just 51 conversions on 202 attempts during the regular season and had four games in which they allowed just a single third-down conversion.

But against a Philadelphia offense that was humming all game, the Vikings had their worst showing of the season as the Eagles converted a whopping 10 of 14 times on third down.

Zimmer said Tuesday that he plans on taking a deeper dive into why Philadelphia was so successful,

"I mean not only (Philadelphia), but anybody that had success against us in the past. I think one of the things I meant was that we'd been great at third downs and they got after us on third down," Zimmer said. "So, we need to figure out 'OK, why were they and how could we do this?'

"That's why I said I could have made some better calls. Sometimes when you're sticking with things, and it's been successful for you, you continue to do it and maybe I did it a little bit too long," Zimmer said. "That's all a part of the process of self-scouting, evaluation, and things as you go forward."

The Vikings defense had a pair of First-Team All-Pro players in 2017 as Smith and Rhodes earned that accolade. Griffen was named Second-Team All-Pro.

Those three players were also named to the Pro Bowl, as were Joseph and Barr.