For the second straight year, Rajon Rondo’s offseason has been filled with turmoil. Where last year his summer was marked by trade rumors and discussions of a poor attitude, this summer has been stained by a mysterious departure from Team USA — a departure that caused many to wonder whether Rondo had actually been cut, and others to wonder whether he still deserves the label “trouble-maker.”

But no offseason turbulence, no unfounded rumors, can change the facts: Rondo now has five teammates who are more accomplished and four who are better-known, yet there is no mistaking that the Boston Celtics are Rondo’s team, and his alone. He is the on-court star, the leader. He is a First-Team All-Defender and an All-Star. He is a champion. And if the Celtics are to win a title this year, if they are to avenge the ghosts of last season, it will be Rajon Rondo who took them there.

“[Rondo has] grown up before everybody’s eyes,” Kevin Garnett said last season, showing faith in his teammate. ““You want your point guard setting the tone every night. You want your point guard leading [you].”

And that’s exactly what Rondo does. Never bashful, he has now lost all hesitancy he once displayed in leading his older, more famous teammates. You can see it in his body language, the way he fiercely points people to spots. You can see it on the court, where Rondo is clearly more confident dictating things. But it’s most visible in the way his teammates ceded the torch.

“You’re talking about a guy who grew up,” Paul Pierce told Sports Illustrated in May, “who had a great year, and once you’re put in that elite class it’s like there’s no more looking down on him.”

No more looking down on him. Not for Pierce, not for Garnett, not for Ray Allen, and not for the rest of the league.

“He always spoke up,” Pierce said. “It’s just that he’s got more ears now.”

Still, there is more growth for Rondo to experience. As well as he played last season, Rondo’s jumper could obviously use work and he needs to prove he can lead a team in the fourth quarter. There’s also a nagging inconsistency to Rondo’s game, an inability or unwillingness to dominate at all times. Maybe it’s nitpicking, but with the way Rondo usually exhibits total control, one wonders why he can’t do it every night, for 48 minutes. Doc Rivers believes Rondo’s tendency to disappear, or at least blend in, has to do with a certain anger.

“The thing Rondo has to still improve on is he gets upset about a guy blowing a play,” Rivers said in May. “And it affects how he plays for the next five minutes. He said, ‘Coach, I’m not mad at you or anybody, I’m just mad.’ I’ve said, ‘Does it really matter who you’re mad at? If you’re mad and you can’t function — I don’t care who you’re mad at, just play and do your job.’

“But as the year’s gone on, he’s made better and better strides at it. He would get so mad at a guy who misses two plays, he’d pout the next six minutes of the game and literally not play. And now it’s one play maybe, or not even, and he’ll catch himself.

“He’s gotten better and that’s really important, because I can see where coaches or even teammates would have taken that personally, like he’s quitting, he just gives in. But he’s not. We had to get that out of him, and this year has been his best year by far.” And if he continues his growth curve, next year should be even better.

From the Big Three to the Small But Dominant One, the balance of power in Boston has shifted. One man is left to lead the Celtics. One man has their hopes resting squarely on his thin but broad shoulders. All indications say he’s prepared for that type of pressure and unworried by it. All signs say he’ll be even better this season.

Offseason turmoil or not, the Celtics are in good hands.