One thing members of this Red Sox management team are fond of saying — besides “ticket prices will increase” — is that every team comes into every season with an entirely different makeup, an entirely different group dynamic.

And of course, they’re correct. Even on the odd chance you brought back the same exact roster from the year before, some of those guys would be coming into their prime, others would be passing theirs, younger guys would be emerging. There’s too much randomness for any two seasons to ever be alike. It’s Chaos Theory at work. A butterfly flaps its wings in Seibu and Daisuke Matsuzaka walks four batters in the first instead of three.

So while I get that, I always kind of felt like that really only applied to teams. That when it came to individual ballplayers, in 100-plus years of pro baseball in Boston, that we’d seen pretty much everything there is to see. Petulant superstars? Been there. Charismatic Latin American ace pitchers? Done that. Disgruntled misanthropes? Old news. Humble leader types who are pillars of the community? Seen it before.

And yet this year with the Sox starting camp we’re witnessing something that as far as I can tell we’ve never seen before. Not with the Red Sox, and I’m pretty sure not with any of the other pro teams in town.

Jonathan Papelbon is leaving at the end of the year. And everyone involved is OK with it.

Before I go any further, let’s just be honest and admit that what I just said is true. Paps himself can issue all the denials he wants and Terry Francona can shrug his shoulders and say he doesn’t know what’s going to happen and Theo Epstein can adopt all the wait-and-see approaches he wants. But he’s going. You know it. I know it. They know it. The guy who cleans the Fenway urinals knows it. My fourth grader with the closet full of No. 58 jerseys knows it. Next to “Qaddafi is a bloodthirsty crackpot who doesn’t put ‘u’s after ‘Q’s”, “2011 is Papelbon’s last year in Boston” has been the worst kept secret on Earth.

So he’s leaving, for sure. But to my knowledge, no star player has ever left town under circumstances like these. Not even close.

Make no mistake — Papelbon is a star. A four-time All Star. Thirty-plus saves in each of his first five seasons. The only pitcher to ever throw 26 scoreless postseason innings at the start of his career. You could pick nits about the blown saves last year and the 2009 playoff debacle. But he’s the best reliever the Sox have ever had, by a long shot.

As matter of fact, I’ll posit the theorem that he’s the only Sox closer since Dick Radatz to put together back-to-back great seasons. Look it up. Bill Campbell? Great for one year before Don Zimmer blew his arm to smithereens. Calvin Schiraldi? One good half year before he collapsed in the '86 World Series. (After that, he was more afraid to throw a pitch than Scooby and Shaggy are afraid of ghosts.) Rick Aguilera and Jeff Reardon were never dominant in Boston. Lee Smith was maddening — a towering presence with massive hands like the claws on a demolition truck who could throw in the upper 90s … but who nibbled on the outside corner, circled the mound, played with the resin bag and nibbled some more. Tom Gordon had arguably the best year a Sox closer ever had. Then Stephen King wrote “The Girl Who Loved Tom Gordon” and they both ended up in the hospital. Derek Lowe? One good year, one train wreck. Keith Foulke? All you need to do is find the podcasts of his Dale & Holley appearances from 2005.

Traditionally, closers have been to the Sox what the drummers were to Spinal Tap: Sometimes good, often lousy, but none of them lasted very long.

So make no mistake, Papelbon has been a superstar in every sense of the word. But what makes his situation unique isn’t the fact that he’s on his way out the door, it’s the manner and tone of his departure. It’s no bad blood. Not a trace of animosity. It doesn’t even feel like a breakup. It’s more of an agreed upon parting of the ways. If this is a divorce, it’s the most amicable divorce in sports history. It’s a Hugh Hefner divorce. We hitched ourselves to the young blonde, got the best years out of him/her we could, but now we’re simply moving onto someone younger. No hard feelings; this was just the plan all along.

Again, I can’t recall a superstar and a team splitting up like this ... nicely. Every other time it’s happened in this town, it’s been less like Hefner and his latest soulmate, and more like Frank and Jamie McCourt.

And when it comes to writing the Encyclopedia of Messy Sports Breakups, Boston has been Funk & Wagnalls. (Note to those under 25: Look it up in Wikipedia. Then look up “irony.”) We’ve had every kind of contentious split imaginable: We’ve had the superstar the owner dumped because he was fed up with him (Babe Ruth). The beloved legend everyone wanted that the GM mistakenly traded because he got duped by a crooked agent (Bobby Orr). The underachieving egomaniac who cashed in elsewhere, then got on steroids and resurrected himself too late to do us any good (Roger Clemens). We’ve had the guys who were let go after being replaced by younger talents (Drew Bledsoe, Johnny Damon). Dozens of examples of shocking departures that came out of nowhere (Lawyer Milloy). But mostly we’ve had the kind where the player and management can’t reach a deal, it gets ugly, things get said that can’t be taken back and you just can’t wait for it to be over (Mo Vaughn, Ty Law, Asante Samuel, Randy Moss, et al.). Those are the worst. And like any messy divorce, it’s always the innocent who suffer most. Meaning you and me.

But again, the Papelbon-Sox break up has none of that. It’s just been this understanding all along that this is how and when it would end. Cinco Ocho can give us all the whoknowswhatwillhappens in the world, but he can’t take back five or so years of saying he’s willing to keep taking one-year deals, roll the dice that he stays healthy and then see what the market will bear.

Not only doesn’t this bother me, I think it’s admirable. I really do. It’s refreshing to hear an athlete come right out and admit he’s looking to get the best deal he can. The reason it’s on my bucket list to see Clemens get led away in handcuffs isn’t for juicing or lying to Congress or anything of the sort. It’s because he didn’t have enough respect for the public to level with us. Every deal he ever signed wasn’t for the money. It was always because of his admiration for Drayton McLane or his love of Andy Pettitte and Joe Torre or because Toronto was closer to Texas than Boston is or some such crap.

It was an insult to our intelligence. Just like when Vaughn infamously said, “It’s not about the money.” Is it always about the money? No. Just look at guys like Cliff Lee who left $50 million Yankee bucks on the table to go back to Philly. But sometimes it is about the money. And when it is, just level with us. Which Papelbon has from the jump. And I appreciate the candor.

Look, I know that his honesty about this has chapped some asses around here. I’ve talked to no shortage of guys who think Papelbon talks too much about his contract situation. But I don’t agree. And besides, so long as he’s giving maximum effort on the field, and I have every reason to think he is, why should I mind? Just because I happen to spend too much time neglecting my writing to play “Angry Birds” doesn’t mean I have the right to begrudge someone who’s actually great at what he does to cash in.

And that “talking too much” thing that Paps gets accused of all the time happens to be one of the things I’ve loved best about the guy. I’m sorry, but I like my closers to be slightly nuts. With the possible exception of Mariano Rivera, closing baseball games is not for the sane. On baseball’s “A-Teams,” they’re typically the Murdochs — wild, dangerous nutjobs. But if you’ve got one who can come through for you in the clutch like Papelbon has, you need to embrace the nuttiness and appreciate what you’ve got.

So, he’s leaving. We’ve known that for some time now. And to its undying credit, the Sox front office has prepared for it by grooming Daniel Bard and bringing in Bobby Jenks for insurance. That should smooth the transition and make this all go as painlessly as possible.

Of course, the best way this could go is with another championship. If Papelbon closes out another World Series, no one could possibly hold it against him if he leaves. Unless he goes to the Bronx, in which case forget everything I just said.

Follow Jerry on Twitter @jerrythornton1