NFL playoff storylines to keep an eye on

The 2017 NFL season opened with a shocking Kansas City win at Foxborough. Since then, the Chiefs and Patriots have gone in different directions, but both teams played well to close out the regular season. As the No. 4 seed, the Chiefs would most likely visit New England again in the AFC divisional round, which will at least make Pats fans nervous.

Arguably the best game of the year was Week 15's epic matchup between the Patriots and Steelers decided on a instant replay change and subsequent New England interception. The win by the Pats gave them home-field advantage in the playoffs, which could certainly make the difference if the two teams meet again in the AFC Championship Game. If Pittsburgh fans have reason to be optimistic, their defense did hold up better than usual in the most recent game by switching to man coverage.

Backup quarterbacks are one of the storylines in the NFC, as the two top seeds are headed into postseason with different men under center than the ones who started the season. Case Keenum has been a solid player for Minnesota, which leans on its defense, but his lack of playoff experience is a huge question mark. Nick Foles came on to replace an injured Carson Wentz late in the year and has struggled, so Eagles fan have reason to be concerned.

Many aren't sold on the Jaguars given that they've been through nine straight losing seasons and still have Blake Bortles under center. Still, they finished the regular season with the second biggest point differential in the AFC and the best defense. Getting a home matchup against a potentially LeSean McCoy-less Bills squad, Jacksonville could have a chance to get its bearings before heading into Pittsburgh, where the Jags have already won this season.

The Rams are basically the NFC version of the Jaguars, seeing a complete turnaround this season. They've been solid on both sides of the ball with potential the league MVP in Todd Gurley. Like the Jags, L.A. had the second best point differential in its conference, but the Rams are also starting a second-year quarterback in Jared Goff.

The old saying that defense wins championships has been valid in many years, though the best defenses in this year's playoffs (Jacksonville and Minnesota) have major questions on offense. Can they overcome them and get to the Super Bowl?

An NFC South team has been the conference representative in the Super Bowl in each of the last two years, and the division has a good shot again this year with three teams in the playoffs. New Orleans is back in the postseason as the division leader, while Super Bowl 50 participant Carolina has plenty of ability and experience and Atlanta won its way into the dance late in the year.

Pittsburgh's defense has been solid overall this season but has certainly felt the loss of linebacker Ryan Shazier. After losing him against the Bengals in Week 13, the Steelers allowed 5.8 yards per carry vs. the Ravens, 4.1 yards carry vs. the Patriots and 6.3 yards per carry vs. the Texans. The AFC is loaded with strong running games that could give the Steelers problems.

Drew Brees has remained a top passer, but the Saints' offense has had more balance than usual this season with the arrival of rookie Alvin Kamara and a great year from Mark Ingram. The Saints ranked fifth in the NFL in rushing and second in yards per attempt, while Brees threw for the fewest yards of his New Orleans career. Still, Brees has plenty of experience to turn it on during the playoffs.

Every year there's some nervousness about a Brady decline given his age, and every year he proves the doubters wrong. He had another great regular season with 4,577 yards and 32 touchdowns at age 40, and the Patriots will need him to be at his best again.

Brown exited in Week 15 with a partially torn calf. Fortunately, the Steelers have an extra week for him to rest with their first-round bye, but it remains to be seen if he will be 100 percent in the playoffs.

It's been quite the Jekyll and Hyde act for the Chiefs this season. They started the year going 5-0, including wins vs. the Patriots and Eagles. Then they went 1-6, looking as bad as possible with losses to the Giants and Jets. They've come storming back to going 4-0 at the end of the season, easily defeating Oakland, the Chargers and Miami before beating Denver on the road with backups in Week 17. At their best, the Chiefs have looked like they could beat anyone, but it remains to be seen what version we'll see in the playoffs.

Murray has struggled for much of the season while fighting through leg injuries, putting more pressure on second-year back Derrick Henry. While Henry has held his own, the Titans' offense can be more dynamic if Murray is healthy. He suffered a torn MCL in Week 16 but could still return vs. the Chiefs.

It's been a frustrating year for the Atlanta offense as the Falcons try to re-create last year's historically great unit. Atlanta has scored the fewest points among NFC playoff teams, but the personnel is basically the same as last season. The Falcons started to show flashes late in the year but will need to improve quickly to go on a playoff run similar to last year.

The Chiefs spent big on first-round quarterback Patrick Mahomes this year, and he showed why with an impressive Week 17 performance. He's likely to be the team's starter sooner than later, meaning that Smith is auditioning for other teams and spiking his potential offseason trade value during the playoffs in addition to helping the Chiefs reach the Super Bowl. He could really increase his value with a deep run in the playoffs.

New England's defense has made great strides after struggles early in the year, but the unit still has its weaknesses. In particular, the Pats have had problems stopping the run, allowing the 13th most total yards and ranking second worst with 4.7 yards per carry allowed. With star runners like Kareem Hunt and Le'Veon Bell ahead of them, Pats fans have reason to be concerned.

Buffalo got the help its needed to make the playoffs after Week 17, but not all news was good. McCoy was carted off the field during the team's Week 17 game, and his status for the wild card round is uncertain.

While the Titans' power run game has been successful, their passing game has struggled. The team lost three of the last four games, and third-year quarterback Marcus Mariota has just three touchdowns and three picks during that time. He will need to do better to win at Arrowhead Stadium against the Chiefs.

Harrison was released by the Steelers late in the year and caused a stir by signing with the rival Patriots. The impact he has on the field remains to be seen, but at the very least he could give the Patriots some intelligence behind the scenes.

This could be the end for three Chiefs defensive veterans: Derrick Johnson, Tamba Hali and Darrelle Revis. Revis signed late in the year and has held the Lombardi Trophy with the Patriots, but Johnson and Hali are still trying to get their first. The two have been Chiefs for their entire careers and could retire following the season. They would like nothing better than to walk off as winners.