Everybody knows Rajon Rondo doesn't do "normal."

Perhaps that's why the unusual method he used to announce his return date on Twitter hardly raised an eyebrow across the league:

To be clear, everyone in NBA circles recognizes the significance of Rondo's return from a torn ACL, which he communicated by sharing the number of seconds that will have elapsed between his injury and his first game back on Jan. 17. But nobody was surprised to see him communicate that information in such an oddly cryptic way.

Rondo's a different breed, with a personality that falls somewhere on the spectrum between "quirky" and "downright weird."

Figuring him out isn't easy, but maybe an examination of the peculiar tendencies and contradictions that make up his personality will help shed a little light on the league's most unusual star.

Definitely, Definitely Sharp

I doubt a broad poll of NBA players' off-court interests would reveal "math" as a strong favorite. Rondo, though, might have more than a little Rain Man in him.

Everyone knows about his penchant for Connect Four, a strategy game for kids that is basically a more complicated version of tic-tac-toe. But Rondo is passionate about it, perhaps drawn by the appeal of probability and sequence.

He's also apparently a card shark.

Per Baxter Holmes of The Boston Globe, teammate Brandon Bass spoke of Rondo's legendary analytical mind: "When we’re playing Spades on the plane, Rondo is able to count the cards and figure out pretty much what everybody has in their hands from the cards being played."

Those Rain Man comparisons don't sound so hyperbolic now, do they?

We toss around the term basketball savant pretty loosely, but Rondo might warrant that label—if only to do justice to his off-court hobbies.

Does and Does Not Play Well With Others

Rondo's ability to master mathematics and complex strategy doesn't extend to the less rigid rules of interpersonal communication.

Put simply, Rondo has a reputation as being aloof, standoffish and sometimes a little difficult to deal with.

Chris Sheridan of Sheridan Hoops reported over the summer that Doc Rivers' desire to leave Boston might have been tied to more than fear of leading a lottery team:

It isn’t just that he doesn’t want to be a part of a rebuilding situation; it is because he has an intense dislike for point guard Rajon Rondo.

A source close to the Celtics tells Chris Sheridan of SheridanHoops.com that Rondo dropped an F-bomb on Rivers in the locker room during a team meeting, and Rivers went after Rondo and tried to fight him before the fracas was broken up.

Even before that, there were rumors that Rondo and his teammates didn't always see eye to eye. Chris Mannix of Sports Illustrated chronicled one such saga involving Ray Allen.

"It's pretty simple," said a source close to the team. "They hated each other. And there was no way Ray was coming back as long as he [Rondo] was there."

Whatever difficulties Rondo has in relating to his co-workers, they certainly don't extend into other areas of his life. The truth is that he's not really a bad guy, nor is he an inherently unpleasant person.

Based on the immense amount of charity work he does, we can safely conclude that he's actually a good dude, concerned with helping out his community and devoted to some admirable causes. As Bleacher Report's Jared Zwerling tweeted, he's been honored for that dedication:

Aside from the occasional mention of fashion or late-night snacks on his Twitter feed, Rondo typically shares images of his philanthropic efforts:

You'll note he's genuinely smiling in all of them:

Rondo defies the conventional good guy/bad guy divide. He's apparently hard to get along with at work, but a virtual saint elsewhere.

Conundrums Continue

On the court, Rondo is just as odd and contradictory.

His pregame rituals are genuinely neurotic, as former teammate Jason Terry explained to ESPN Boston:

His routine is long-winded and it lasts all the way through tip-off. It starts in the back hallway. He runs down a corridor and he throws the ball to our team chaplain, who throws it back. Then [Rondo] runs out into a circle, high-fives the whole team and then he does the layup lines for five minutes. 

Then he will stand under the goal and Paul Pierce will shoot every ball on the rack from half court. Rondo will catch four balls at one time and then after that, it's just amazing -- one pass off the backboard to KG, one bounce pass to Paul Pierce and then he throws it all the way up to the scoreboard and Jeff Green finishes with an alley-oop. 

It's every game, even road games.

The quirks don't stop there, either. Check out this clip of Rondo's mesmerizing routines after the opening tip.

This guy just refuses to do things conventionally.

That's the case for his actual game, as well.

Rondo possesses unlimited, freakish athletic talent. He's got a terrific handle, long arms, huge hands and a uniquely creative style. Yet he's not a guy who forces the issue; instead, he prefers to set up teammates.

This is, perhaps, the strangest incongruity of all. Rondo, a person with a well-documented history of interpersonal discord, simply wants to create scoring chances for others.

Maybe that's just another symptom of his analytical mind. Perhaps he recognizes the actual value of facilitating and opts for that strategy because it makes the most sense—not because he cares about endearing himself to teammates.

For what it's worth, Rondo's grasp of basketball nuance is the stuff of legend.

Per Adrian Wojnarowski of Yahoo! Sports, he's always had a staggering capacity to memorize sets and tendencies:

Rondo was a young guard during the Celtics' championship chase in 2008 when a teammate remembered one of the coaches giving him a Hawks playbook to study overnight. They were in the opening-round series, and the coaching staff outlined the top 15 or so plays Atlanta would likely run on Rondo.

The next day, the coach quizzed Rondo on the plays. He asked about three or four, and Rondo ran through the details for him. And then, the coach asked about another play in the book – only Rondo shot back that it wasn’t in the book, that the Hawks didn’t run the play. Which was exactly what the coach wanted to hear.

What if Rondo simply views everything in his life as some kind of strategic exercise—like Connect Four or spades—meant to be analytically dissected? That would certainly explain why he has such a firm grip on hoops but a looser understanding of how to get along with people; one lends itself to mathematical understanding while the other doesn't.

Then again, that doesn't square with his charitable endeavors. So we're back where we started with Rondo, which is to say: We still don't understand him.

Authenticity

There's one thing about Rondo that isn't quirky or odd or contradictory, though: He's real.

In a league where players are consumed with the idea of building a brand and creating an image, Rondo stands out for his authenticity. After all, nobody would purposely cultivate the reputation he's built for himself.

Maybe he's a little weird, but at least he's being himself. The league will be better off with one of its most genuine, if complicated, players back on the floor.