With just 16 regular season games in an NFL season, a five-game losing streak is really hard to overcome.

When that skid comes within the first six games of the season, playoffs are generally a pipe dream.

However, the Kansas City Chiefs overcame a 1-5 start -- and an injury to superstar running back Jamaal Charles -- to finish the year 11-5.

What went so right for the Chiefs that they were able to reel off 11 straight wins -- and 12 if you include their wild card win over the Houston Texans?

What Went Right?

The Chiefs wound up with the second-best rushing attack in the NFL, per our Net Expected Points (NEP) metrics.

NEP, if you don't know, indicates how a team performs relative to expectation-level. While a two-yard run will look pretty bleak on a yards-per-carry basis, if it came on 3rd-and-1, it was a good play. NEP rewards such instances even though traditional stats won't.

So when we adjust for opponent strength, Kansas City generated 0.09 points per carry. Only the Buffalo Bills (0.10) were better.

How did they do it with a three-headed attack? Well, all three of their running backs fared pretty well, per our metrics, among the 58 backs with at least 70 rushes.

Yes, Charcandrick West, the team's top back in terms of touches, was roughly an average runner relative to this group, but both Jamaal Charles and Spencer Ware were top-10 talents -- particularly Ware.

It also helped that Alex Smith finished second in Rushing NEP among quarterbacks (34.72).

On defense, the Chiefs really performed well, finishing fifth in schedule-adjusted defensive efficiency on a per-play basis. Their pass defense ranked fourth, and their rush defense ranked eighth.

With a top-two rushing attack and a top-eight defense overall, against the pass, and against the run, it's no wonder that the Chiefs were able to reel off a dozen straight wins.

What Went Wrong?

The easy criticism here pertains to Alex Smith, who finished 19th among 37 passers with at least 200 drop backs in Passing NEP.

He also ranked 19th in per-play Passing NEP and was 21st in Passing Success Rate (the percentage of drop backs that led to NEP gains for the Chiefs).

That's about as close to average (again, 37 qualified passers) as we can get.

This also limited the upside of two potentially elite playmakers: wide receiver Jeremy Maclin and tight end Travis Kelce.

Maclin finished 19th in Reception NEP (87.29) among 32 receivers with at least 100 targets, and his big-play ability was pretty limited, as his Reception NEP per catch (1.00) ranked just 26th. He was a middling 17th in Reception NEP per target (0.70), too.

As for Kelce, he wound up eighth in Reception NEP (61.27) among 28 tight ends with at least 50 targets -- and Tyler Eifert, one spot above him on the list, was a roughly 10 points (72.15) better than Kelce was.

Kelce finished 18th in Reception NEP per catch (0.85), which was lower than players such as Will Tye (0.87) and Jacob Tamme (0.90). Only 80.56% of Kelce's catches led to NEP gains for Kansas City, which ranked 16th in the group.

The elite playmaking ability was severely limited. That can't all go on Smith, but things need to be sorted out if they want to cash in on one of the best run games and defenses in the NFL.

What's Next?

The Chiefs have been pretty aggressive this offseason so far.

They've signed Kelce to a five-year deal, franchise tagged safety Eric Berry, re-upped linebackers Tamba Hali and Derrick Johnson, and signed tackle Mitchell Schwartz, one of the best moves of the offseason.

They needed to do that because they have the fifth-highest salary cap in the league and the 28th pick in the 2016 NFL Draft.

For a loaded team, one that our metrics saw as the NFL's seventh-best squad last season, those limitations should be welcomed, as the Chiefs seem primed to be AFC West favorites entering the season.