SANTA CLARA -- Jim Harbaugh's players know him best, because he is still essentially and eternally part of them, and not exactly one of the calmer examples of them.
He screams along with them, tosses practice passes to them, pushes them, and is immersed in it with an enthusiasm unknown to mankind, as Harbaugh himself might put it.
He's a manic 50-year-old kid having a blast ... who just happens to be in charge of the whole deal.
"Always the same guy with us -- good," said 49ers tailback Frank Gore of his coach. "I'm a football player. He loves football guys."
Or as backup quarterback Colt McCoy said of his coach: "I think if he could still play, he would."
But Harbaugh's players also probably know him least, in some ways, because they don't deal with him when he's away from the locker room and playing field, when anything can happen and any mood can strike.
Put him in any other situation -- with the media, with team employees, with anybody not connected to winning this game right this instant -- and Harbaugh sticks out like a wild rhino among a horde of house pets.
He can't help but bounce around, make noise and maybe rumble over a few people, it's just who he is.
He can't help but seem strange at times, because he doesn't care about hiding whatever he's feeling, and what he feels can range from incredibly exuberant to flat-line somber.
"I'm moody and complicated," Harbaugh has repeatedly said to describe himself, without irony.
No, he was simply born to be a football Mozart, with the temperament.
That's the Harbaugh the rest of the world sees every time he steps to a podium and either banters with reporters, battles with us, quotes Judge Judy at high decibel or performs some memorable combination of all of the above.
When he gave CSN Bay Area's Matt Maiocco a bear hug and then kissed the Sacramento Bee's Matt Barrows on the head after Sunday's victory in Green Bay, well, that was just another gloriously Harbaugh pure public moment.
This is the guy who chattered on about "gobble, gobble, gobble turkey from jive turkey gobblers" last year; the guy who treated the questions about coaching in the Super Bowl against his brother John as if they were brutal inquisitions.
"I've never really seen him with you guys," guard Alex Boone said with a smile. "I can imagine it, though."
It's the impulsive kid, blessed with football genius, barreling through an essential football life.
It's also the guy who turned around the 49ers and now has coached them to three playoff trips in three seasons.
If the 49ers beat Carolina on Sunday, they will have reached the NFC Championship Game in all three of Harbaugh's seasons.
You can't separate Harbaugh's behavior from the success, because it's all the same package.
It's the ruthless competitiveness; it's the manic, overflowing drive to defeat anybody who isn't on his side, which means everybody who isn't in that locker room with him.
He can wear on everybody around him ... but imagine how his opponents feel having to go up against him.
He's secretive, but randomly expansive; argumentative but occasionally happy to talk it out; ferociously driven and ambitious but with no hidden agendas.
He's not Nick Saban or Bill Belichick; the unpredictable Harbaugh can be 100 times goofier and giddier than either of those two dour high-achievers.
He's not as engaging as Bill Walsh; he's not Buddy Ryan or Bill Parcells, who often were bullies with a wink.
There are no proper comparisons to Harbaugh, who has zero interest in being similar to anybody else.
"The thing I appreciate about him and a lot of the teammates (do) is, he's a real person," quarterback Alex Smith once said of Harbaugh.
"He doesn't fake anything. He doesn't try to be anything he's not. He is himself all the time, 24/7."
And that has always shaped my relationship with Harbaugh, too, by the way.
Harbaugh has been less than thrilled with me occasionally, but has gone out of his way to chat with me more than a few times, and I don't think he ever has to guess why I'm asking what I'm asking.
Dave Flemming, a Stanford broadcaster when Harbaugh coached there, and I have a standard rule: You get the best responses from him when you ask him direct questions; gratuitous lead-ins only get him to wonder what the questioner is hiding.
It's all about angles and Harbaugh only wants to deal with things that help him win games. To him, almost all else is barely worth tolerating.
But when he wins, it's euphoria.
"Man, I've seen a lot of happy times with him," linebacker Ahmad Brooks said. "We've won so many games under him and last year we made it to the Super Bowl, when we won the NFC Championship ... when we won this game (in Green Bay).
"I've got a lot of memories with him, just winning."
That's all Harbaugh wants to do -- win, coach, bellow and compete. Everything else? Just part of Mozart's unruly performance.