We've made it to the 2019 NFL playoffs. After 17 weeks of ups and downs and overreactions of all kinds, the playoff matchups are set. From here on out, there's no more speculation or projection -- only proof. You win, you keep playing. You lose, you're done.

But there's still some mystery about this whole endeavor, and more than a few questions this NFL postseason will help us answer. Let's take a look at five of them:

Is this Tom Brady's last run in New England?

There has been plenty of speculation about whether Brady, 42, would leave the Patriots at the end of this season, either via retirement or to finish his career elsewhere. His contract structure allows him to leave if he so desires. There are potentially interesting win-now situations with possible starting quarterback openings in places such as Chicago, Los Angeles, Tennessee and Las Vegas, to name just a few. The possibility exists that Patriots offensive coordinator Josh McDaniels could leave for a head-coaching job elsewhere. There has always been the possibility, however remote, that 67-year-old Patriots coach Bill Belichick could walk away at some point.

So much long-term uncertainty hangs over this New England playoff run, which could be done in by short-term concerns about whether the offense has enough to propel Brady and Belichick to a seventh Super Bowl title. Sunday's events, which saw the Patriots lose to Miami and fall out of the No. 2 seed, makes things that much more difficult, as they now have to play on wild-card weekend for the first time in 10 years.

Whether this run ends with a Lombardi trophy presentation in Miami in early February or with a disappointing earlier exit, one of the major storylines of this offseason will be what Brady wants to do, and whether he wants to continue doing it in Foxborough.

Is this finally Andy Reid's year?

Andy Reid appears to have a Super Bowl-caliber roster. Is it his time to win one? Ron Chenoy/USA TODAY Sports

The second-best coach of his era, Reid is making the 15th playoff appearance in his 21-year head-coaching career. But he has yet to win a Super Bowl, and he has coached in only one. Last year's Chiefs got Reid agonizingly close, as they were one third-down stop from knocking off the Patriots in Kansas City in the AFC Championship Game but ended up losing in overtime.

Reid has the quarterback, in reigning MVP Patrick Mahomes. He has the fastest offense in the league, deep at every position and loaded with explosive playmakers. He has a first-round bye, as a result of Sunday's win and the Patriots' loss. Lately, he has a defense. Before giving up 21 points in a win against the Chargers, Steve Spagnuolo's unit entered Sunday's game allowing a league-low 9.6 points per game over the previous six weeks.

If that defense can keep playing the way it has over the season's final two months, the Chiefs can beat anyone.

Can the Saints avoid the kind of bizarre calamity that seems to knock them out of the playoffs every year?

It's not crazy to think that, but for Stefon Diggs' miraculous winning touchdown catch two years ago and a cataclysmic, rule-altering missed pass interference call in last year's NFC Championship Game, the Saints could be trying for their third straight Super Bowl title. That's how good they've been during their current run, and they are one of the favorites to represent the NFC in in the Super Bowl this season.

NFL PrimeTime on ESPN+ NFL PrimeTime continues this postseason with extended highlights and analysis following the conclusion of each day's playoff games. Watch on ESPN+

But if you remember those old Peanuts cartoons where Charlie Brown tried to kick the football and Lucy kept yanking it away from him at the last second, you know what it has been like around the Saints the past couple of Januarys.

Like Brady, Saints quarterback Drew Brees is on the other side of 40, and there are legitimate questions about how much longer he'll want to do this. But he has been playing at a high level over the past few weeks. He has a ridiculous connection with Michael Thomas, who's the best receiver in the league right now. He has an emerging connection with tight end Jared Cook, who could be the dynamic non-Thomas threat the Saints have lacked. The run game looked better with Alvin Kamara getting going in Nashville in Week 16. And the defense gets after opposing quarterbacks.

The Saints were 7-1 on the road this season, so having to go to someone else's building in January shouldn't bother them. Maybe the third time is the charm and this is the year Charlie Brown finally connects.

Can anyone stop Lamar Jackson and the Baltimore Ravens?

There's been a lot for Lamar Jackson & Co. to smile about this season. Scott Taetsch/Getty Images

The Ravens gave their star quarterback and a number of other players a well-earned day off Sunday, and we won't see them again until the divisional round. Baltimore has secured home-field advantage throughout the AFC playoffs, and the Jackson-led rushing attack has been more or less unstoppable all year. The Ravens on Sunday set the NFL record for rushing yards in a season with 3,172, passing the 1978 Patriots.

Baltimore is 5-1 against other playoff teams this season, with victories over potential AFC playoff opponents New England, Houston and Buffalo as well as San Francisco and Seattle in the NFC. They lost 33-28 in Kansas City in Week 3.

In last season's playoffs, the Ravens fell apart against a Chargers team that was facing them for the second time. It remains to be seen whether a second look at these Ravens would help a team like the Patriots or Texans. But it also seems clear that what Baltimore is doing is a lot different and more sustainable than what it was doing this time last year.

Can Carson Wentz keep this Eagles run going?

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Wentz is forever in the unprecedented situation of having to live up to his backup. It was Nick Foles who delivered the Eagles their first Super Bowl title two seasons ago when Wentz got hurt and couldn't finish the year, and if Wentz never wins his own, he'll have to spend his career in Foles' shadow, at least to some degree. Wentz proved a lot with the December run that got the banged-up Eagles into the NFC playoff field, but the standard in Philly is higher at this point than just an NFC East title.

These Eagles are likely not the team to make a run, in part because of how shredded they are at positions such as wide receiver and cornerback, and in part because of how strong the rest of this year's NFC field looks. But they have shown, by getting themselves into the playoffs with late-season runs each of the past two seasons, that they have a lot of toughness. And as the Bears found out a year ago, they aren't an easy out come playoff time.