As a football decision, parting with Alex Smith should be easy. No team on the rise with a second-year coach and more hope than the franchise has had in two decades can keep going with a 36-year-old quarterback just back from a catastrophic leg injury who missed three of the season’s final four games with another injury to that same leg — especially when that quarterback has almost $40 million left on his contract.

But nothing is easy or just about football when it comes to Smith. Letting him go is a complicated unraveling of the threads that have held the Washington Football Team together through a year like none an NFL team has experienced. Pulling too many of them out could end the good work done through the chaos and send the organization tumbling back into darkness.

The problem is that Smith has become two separate and indispensable people to this team: the quarterback who finds ways to win games, and the leader who makes every player believe he can do more. Almost all the winning — the four straight victories in November and December, the NFC East championship — is because of him. Replacing him is almost impossible, as Washington Coach Ron Rivera tried to explain Sunday.

“Well, you’re going to have to find a guy that has those same types of intangibles,” Rivera said. “Those guys are special. They only come around every once in a while.”

Still, if Washington is going to build off the promise brought by a young group of potential stars, creating what Rivera has repeatedly called “a sustainable winning culture,” it needs a quarterback who at least can take it through the next two or three seasons. Perhaps had Smith’s calf injury not occurred, Rivera could have felt comfortable with starting him next season and drafting someone to eventually take over. But this latest injury leaves everyone with serious concerns about his ability to last a full season.

Rivera now faces the most wretched of dilemmas. He can’t build a Super Bowl contender with Smith as his quarterback, but his team has yet to show it can win behind anyone other than Smith.

Rivera and Smith were vague about the future during their season-ending video conference calls Sunday. Rivera said he is going to talk to the team’s owner, Daniel Snyder, about his “intent going forward” — an implicit suggestion that he will ask Snyder (who is fond of Smith) for permission to find another quarterback. Likewise, Smith said he wants to take “a few weeks” to decide if he wants to keep playing, adding that he wants to get “input” from his wife and children, who had to endure medical trauma from a serious infection in his leg, his more than one-year recovery and the fear that comes with watching him get hit again and again on the field after his return.

The whole thing is made messier by the fact there is clearly a part of Rivera that does not want to let go of Smith, and a part of Smith that doesn’t want to let go of the game. Smith’s return this fall seemed to surprise them both, with neither sure Smith’s gutted and rebuilt right leg would hold up when hit in a game. Then, when it did and Smith brought calm and eventually winning to a team seemingly headed nowhere, they rode the good times together, rarely speaking, at least publicly, about tomorrow.

But that tomorrow has arrived, and like many things around this franchise over the past 20 years, the whole situation is a convoluted quandary. Rivera is looking to start over at quarterback without the best team leader he might ever have, and Smith, after pushing himself to make an impossible return come true, is tepidly confronting his athletic mortality just days after coming back to lead a team from 2-7 to a division title.

More than once in recent days, Smith has talked about the joy of this season and the rush that comes from fighting through games, trying to find ways to win and making the players around him better.

“You certainly cannot find it anywhere else,” Smith said last week when asked about this thrill, adding, “You can’t duplicate it.”

“Shoot, I can’t imagine him not trying to play football next year — just the type of person that he is,” said tight end Logan Thomas, who has become friends with Smith. “He loves the game.”

Who knows what lies in the plan Rivera will present Snyder. Maybe he knows exactly whom he wants to bring in to jump-start the winning. Perhaps he wants to acquire Cam Newton, who led him to three NFC South titles and a Super Bowl appearance with Carolina; or trade for someone such as Detroit’s Matthew Stafford; or sign a journeyman starter good enough to muddle through the next couple of years while figuring out a long-term solution.

Whatever that plan is, it doesn’t seem to involve a quarterback on the current roster, including Smith, whose departure would take $13.6 million off the coming year’s salary cap but leave a vacuum that few quarterbacks can fill. It’s not an easy decision. But after an agonizing year during which an old quarterback given up for done saved Rivera’s first season with Washington, Rivera seems to sense he has to look for a new quarterback now.

And the really hard work is about to begin.