Amazing what one big win can do for a flagging franchise trying to find its footing.

After the Seahawks had lost two straight home games for only the second time with Russell Wilson, they were on the outside looking in at the postseason picture. But they quickly dug out of the slump with an upset victory over the NFC’s top team, Philadelphia.

Now the Hawks (8-4) suddenly own their destiny again, and Atlanta helped their pursuit of a top-two seed by knocking off the Saints on Thursday night.

Before they lost to Atlanta three weeks ago, the Seahawks had a 61 percent chance to make the postseason, a 38 percent chance to win the NFC West and an 11 percent chance to claim a first-round bye — according to aggregate projections by Five Thirty Eight, the New York Times and Football Outsiders.

The Seahawks have gone from 6-3 to 8-4 since then, with the victory over the 10-win Eagles, but Seattle still has just a 3.3 percent chance of a bye and a 36 percent shot at beating the Rams (9-3) for the NFC West, per the 538/NYT/FO aggregate. Their playoff chances have bumped up to 75 percent, though.

Let’s see what needs to happen for each scenario:

FIRST-ROUND BYE

The Seahawks clearly have to win their final four to be in the hunt.

Minnesota (10-2), Philadelphia (10-2) and New Orleans (9-4) all have the edge on them for the top two seeds. They need lesser-record teams to beat those clubs the rest of the way, which is why the Hawks had to be happy the Falcons held off the Saints 20-17 on Thursday.

It looks almost impossible for the Vikings to get bumped from the top two. They are at Carolina, home to Cincinnati, at Green Bay and home to Chicago. Even two NFC losses in that set probably wouldn’t demote them.

The Eagles have a tough one at the Rams this week but then finish with three winnable games — at the Giants and home vs. Oakland and Dallas. The Seahawks would need a loss to the Rams and an upset in one of those final three to bump the Eagles down to 12-4 — although a three-way tie that included the Saints could keep Seattle out of the top two.

The Saints face Atlanta once more and also host the Jets and finish at Tampa Bay. If they lose one more and the Eagles stumble, it would open the door for Seattle to streak to the second seed.

DIVISION

To win the West and get a home game, it’s a simple matter of beating the Rams in Seattle next week and otherwise keeping pace with Los Angeles.

The Rams play the Eagles this week and also play at Tennessee and home vs. San Francisco.

The Hawks don’t have to beat the Rams to win the division though. If the Rams drop two other games — e.g, to the Eagles and Titans — and the Hawks win the rest of theirs, they would both end up 11-5 and Seattle would win the common-games tiebreaker (or division tiebreaker if the Rams lost to the 49ers instead of the Titans).

Likewise, the Hawks could beat the Rams and not win the division — if Seattle loses another game and the Rams win the rest of theirs. So the Week 15 meeting is not technically for the division title, but it would obviously help Seattle’s playoff chances.

PLAYOFFS

The Seahawks are the No. 1 wild card (fifth seed) at the moment, but Carolina and Atlanta are hot on their heels and the Falcons own a head-to-head win against the Hawks.

Seattle is helped by the fact that the NFC South contenders play each other in the final four weeks — the Falcons facing the Saints again and Carolina. It’s possible that all four teams end up 11-5, in which case Carolina would be the odd team out.

Basically, Seattle would be locked in with three more wins.

A 2-2 finish, though, would make it tough. In one scenario, Seattle, Dallas and Detroit all miss the playoffs at 10-6 — aced out by the NFC South teams. In another 10-6 variation, Detroit knocks out Carolina and Seattle (via common games).

Seattle could get in at 10-6 if only one of the two losses is to an NFC team. One scenario puts them in as the sixth seed in a conference tiebreaker over Carolina. Another sets them as the six behind Carolina.

Bottom line: The Seahawks really need to win at least three of the last four to be assured of a playoff spot. Anything less and they will need help.