The Cowboys surprised most in 2016 by capturing the NFC’s top seed behind exceptional performances from rookies Dak Prescott and Ezekiel Elliott. In 2017 they won’t surprise anyone, and it won’t matter. Dallas is the team to beat in the NFC.

This is more than a little premature; after all, NFL free agency will drastically alter the NFL landscape, and the Cowboys are proof about the difference the draft can make on a team’s immediate production.

It’s also very easy to look at the Cowboys and see a team with a huge window that just opened up. Adding Prescott and Elliott behind an offensive line anchored by an absurdly youthful group of studs -- Tyron Smith (26), Zach Martin (26), Travis Frederick (25) and La’el Collins (23) aren’t even in their primes yet -- completely flipped the script of how we believed this team would approach each season.

Jerry Jones was mortgaging the future for one last run with Tony Romo virtually every year and then he struck gold in the draft and set up the Cowboys for the long haul. The Cowboys should have a five-year Super Bowl window with this core of offensive players.

On the other hand, ask someone like Dan Marino how long a window in the NFL really lasts. In his second season in the NFL, Marino threw for more 5,084 yards and 48 touchdowns, leading Miami to the title game. The Dolphins would lose to the 49ers but surely they’d be back a few more times with their 23-year-old quarterback winging it around. Marino would never appear in another Super Bowl.

It’s a cautionary tale worth remembering, but one that might not really apply for Dallas, a team positioned to be the best in the NFC this year. Let’s examine why.

The offense is loaded for the long haul

The age and talent on offense for the Cowboys heading into 2017 is just incredible. Elliott is a top-five running back after just his first season. Despite a slow start, he led the league in rushing (1,631 yards), even though he also sat during Week 17.

He is fast, strong, an underrated catcher, a tremendous blocker and if he gets in the open field he is going to leave you hanging.

Elliott basically patented the “I’m more athletic than you” hurdle in his rookie season.

The only real concern for Elliott is the wear and tear of a long rookie season. He also led the NFL in carries (322) and the NFL has not been kind to running backs who blow past an admittedly arbitrary 300-carry number.

The Cowboys’ willingness to run Zeke like that in the regular season made their decision to limit his playoff carries (22, when he was averaging 5.7 yards per carry against the Packers’ nickel defense) even more surprising. Finding talented backups to lessen his regular-season load is a must to keep him healthy for the long haul and the future.

On the offensive line, there’s little change coming. Ronald Leary is a free agent and, at age 27, will probably find plenty of interested suitors on the market. The Cowboys thought about dealing Leary before the season for defensive help but held off -- and when Collins went down with a toe injury, they were bailed out in a big way. Doug Free (33) is the only lineman over 27 and has one more year left on his deal. The Cowboys need to continue finding depth in the draft and injury regression could be a concern, but by and large there is no reason to expect the offensive line to struggle in 2017.

If the line holds up its end of the bargain, there’s a trickle-down effect on the rest of the offense.

No sophomore slumps

It’s not unreasonable to be concerned with Prescott taking a step back. He was phenomenal for a quarterback, and not just a rookie quarterback. Prescott broke Tom Brady’s record for consecutive completions to start the season without an interception. Every step of the way, he managed to shrug off critics and step up his game in critical spots.

Even though he made plenty of rookie mistakes, Prescott showed a knack for recovering from them and pulling off clutch plays in big spots.

Nothing was too big for either Prescott or Elliott. Teams will have more time to adjust to the Cowboys’ offensive approach and could potentially limit Prescott. But if the Cowboys are doing what they want to do -- establish the run behind the offensive line with a healthy, dominant Elliott -- then good luck thinking about how to slow down the passing game.

None of this even mentions Dez Bryant. Bryant is still just 28 years old and he looked like his old dominant self for the second half of the season. He averaged five catches, 73 yards and a score in his final seven games (not counting Week 17 when the starters barely played).

A full season of dominant Dez should keep Dak from dropping off too much.

Room to improve the defense

The good news for the Cowboys is the limited losses on offense. Leary, Terrance Williams, Darren McFadden, Brice Butler and Gavin Escobar are the most notable names leaving on that side of the ball.

Defensively it gets a little tougher. Even though Brandon Carr and Morris Claiborne -- both acquired in 2012 during a hyper-aggressive offseason for Dallas -- never lived up to expectations, they are still starting bodies. Barry Church and J.J. Wilcox are free agents as well.

So there’s a lot of work to do. Good news: The Cowboys restructured several contracts to get underneath the projected cap. Bad news: They’re not too far under the projection. Releasing Romo will clear either $5.1 million or $12 million depending on whether Dallas designates him a post-June 1 cut (they could still trade him, but a release seems most likely).

After a Romo cut (post-June 1), Dallas would be at $151.8 million. Add in $5.3 million for the draft and the Cowboys are looking at about $10 million in cap space to work with in free agency. That’s sub-optimal.

That Jaylon Smith pick in the second round looks a lot more prudent right now, doesn’t it? Smith, a linebacker, won’t be playing in the secondary but he could be a “bonus” defensive addition.

The cornerbacks available in free agency actually represent a pretty strong class and there’s ample talent in the draft as well. So Dallas can retool on the fly.

Let’s not forget that the defense wasn’t great to begin with in 2016 either. The Cowboys were a below-average team on defense, but just barely -- Football Outsiders had them at 17th in defensive DVOA for 2016. Not every team is going to be loaded on both sides of the ball, and Dallas showed in 2016 it was capable of providing a defense that is better than the personnel (thanks Rod Marinelli) while also managing to have the offense assist said defense. Clock-chewing drives are your friend.

This is all a very friendly reminder not to judge any offseason moves before we see how they play out in the regular season. The Cowboys were widely expected to be in trouble at quarterback when Romo went down. We saw how that worked out.

The division isn’t drastically improving

The NFC East got a LOT better in 2016. Philadelphia was a frisky seven-win team. The Giants won double-digit games to make the playoffs. The Redskins should have joined them except Kirk Cousins laid a couple eggs late.

But is it getting better again this year?

The Redskins might lose some critical offensive pieces in free agency (Desean Jackson, Pierre Garcon). Washington is going to spend half of the offseason trying to figure out whether Cousins is going to get a new contract. There’s a lot of potential loss in the front seven and the Redskins will need some strong work this offseason to make it a better group heading into next season.

The Eagles will have Carson Wentz in his second year, but there are worries about his mechanics and he’s still lacking in terms of weapons. Jordan Matthews, Nelson Agholor and Dorial Green-Beckham do not look like the answer. Zach Ertz was really good down the stretch but he needs to be more consistent. Philly really needs Lane Johnson to stay on the field.

The defense could be facing some turnover with expected cuts (Connor Barwin) and rumored trades (Mychal Kendricks). Every year is a roster roller coaster with Philadelphia.

The Giants outperformed their roster and Eli Manning didn’t look like himself last year. Odell Beckham got criticized for being on a boat, but he and Sterling Shepard are a strong point on this offense. The running game is not -- Adrian Peterson is perhaps in play, but is he a fit with how many three-wideout and shotgun sets they run? Jason Pierre-Paul could be leaving in free agency, although that unit should still be dangerous because the secondary is one of the best in the league thanks to Janoris Jenkins, Landon Collins and Eli Apple. Losing a presence up front won’t help the back end however.

The East just doesn’t feel as wide open as it usually does this time of year. There’s a lot of ballgame left, but the Cowboys should be considered the frontrunners.