GREEN BAY, Wis. — There’s no rational reason that Jimmy Garoppolo is one game away from making the Super Bowl for the second time in three years.

Not a one.

After all, this is a league where quarterbacks author teams’ fates. Garoppolo is yet to throw a touchdown in this postseason. He has, however, thrown two interceptions and averaged a paltry 151 yards a game.

These are not winning performances. Maybe they could be in the 1970s, but not in this pass-happy league.

And yet there the Niners are, on the cusp of another NFC title.

How is this happening?

I have a theory, and it’s been loosely corroborated by Garoppolo’s teammates, who have done nothing but rave about their quarterback and his leadership abilities over the last few weeks, a continuation of the praise he’s received since he’s come to the Bay Area.

I think that Garoppolo is incapable of internalizing bad play. He exudes confidence — rational or irrational — at all times.

He is the opposite of a head case. And that, paired with the undeniable talent that’s needed to be a starting quarterback in his league, makes him the perfect quarterback for this 49ers’ team.

Yes, it might drive his coaches — all of which are tied up in knots — crazy, but that steady diet of optimism can’t help but rub off on his teammates.

And when the moments are big, there’s no better quality to have than confidence.

Garoppolo has it in spades.

We’ve seen it so many times over his 49ers career — he’s dug the Niners out of a hole that he, himself, dug earlier in the game.

We’ve seen it again and again and again this season. The Niners have been fending off the end of their season since mid-November.

Garoppolo hasn’t particularly played well since the calendar flipped to December — he has seven touchdowns to eight interceptions over his last seven games — but he has authored big drives that helped put the Niners in the playoffs (Week 14 vs. Cincinnati, Week 18 vs. the Rams) and the Niners have gone 8-2 with him at the helm since Week 10.

Other teams — lesser teams — might need top quarterback play to win games.

The 49ers apparently don’t. They’re just that good everywhere else.

San Francisco simply needs Garoppolo to not lose the game. They just need him to continue to feed optimism to the rest of the group.

And while it might be a close call at times, he has done it.

“I’m impressed with his demeanor as a leader,” Nick Bosa said after Saturday’s Divisional Round win over the Packers — a game the Niners won behind a 45-yard field goal as time expired; a field goal set up by another Garoppolo game-winning drive.

“A lot of people give him crap for whatever but he’s as cool and collected as a quarterback that I’ve ever had and he is the perfect guy to lead us to where we need to go.”

No, it doesn’t seem logical. Yes, it hardly seems sustainable. I still believe the proof of quality in the NFL is found in the margins and the margins for the 49ers are razor-thin — they’re always pushing it until the final moment.

But perhaps I’ve been overthinking it.

Perhaps I should simply forget the Xs and oh-no throws and embrace good vibes No. 10 exudes.

The 49ers are a great team. Bosa might be right — the 49ers are so good they don’t need their quarterback to lead the way all game with his play. No, they just need his positive demeanor and an uncanny knack for performing in the clutch.

Let the other team’s quarterback melt under the bright lights. Garoppolo might not have the upside of MVP-candidate quarterbacks, but he’ll still be standing in the end. He just doesn’t get knocked down.

The last three weeks, we’ve seen it play out: Matt Stafford choked away the game for the Rams in Week 18 with a terrible interception late. Dak Prescott refused to push the ball deep and then ended the Cowboys-Niners Wild Card Game with a brainfart. And then on Sunday, Aaron Rodgers was all twisted up, locking onto one receiver and collapsing in the second half.

Each time, Garoppolo was there to either press those opposing quarterbacks or make the most of the opportunity those choke jobs provided San Francisco.

Garoppolo might be a lame-duck quarterback, but he has handled this season with incredible professionalism and class. Don’t forget, he’s played the last three games with a busted thumb, and, for the last six quarters of play, a jammed shoulder.

He deserves a ton of credit for these latest Niners wins.

It doesn’t have to make sense how this is all happening. It just needs to keep happening.

Yes, there’s something magical — stressful, but enchanted — about this improbable 49ers season and Garoppolo is at the center of it all.

How much further it goes is anyone’s guess.

But the fact that it’s made it this far makes Garoppolo’s winning qualities — no matter how peculiar or impossible to define — undeniable.

And perhaps that’s made these 49ers undeniable, too.