The dressing room. The inner sanctum of any sport. What happens inside those four walls stays there - unless it goes too far and into the public domain.
Pietersen's former England captain Michael Vaughan explores the dynamics of driven and dysfunctional dressing rooms in cricket, football and rugby in a BBC 5 live Sport special, which was broadcast on Wednesday at 19:30 GMT.
Burnley manager Sean Dyche, former Wimbledon player and Northern Ireland and Fulham boss Lawrie Sanchez, as well as England Rugby World Cup winner Matt Dawson, help Vaughan reveal some of the secrets of the team environment.
Player power … and the sound of silence
One of football's most extreme dressing rooms was Wimbledon's notorious "Crazy Gang" during the 1980s and 1990s - comprising strong characters such as Vinnie Jones, Dennis Wise, Dave Beasant and John Fashanu, who were renowned for the practical jokes they played on unsuspecting team-mates.
Sanchez entered this intimidating environment in 1984, and sat down next to striker Alan Cork on his first day. "I don't know why you've joined this club; it's a crap club, crap manager, the players are crap, the dressing room's crap," Cork told him.
"I sat there thinking 'what have I done?' But that was Alan Cork and that was what he brought, and there were different characters. There were eight or nine leaders in that dressing room. When they changed manager once I said to [ex-Wimbledon owner] Sam Hammam: 'Why don't you let the players run it?' You could bring in Mickey Mouse and we could run this club by ourselves because we know what we are doing."
You would be hard pressed to find such a voluble, fractious atmosphere among modern-day dressing rooms according to Dyche, who played more than 450 games for half-a-dozen clubs including Chesterfield, Millwall and Watford in a 17-year career that ended in 2007.
"The mentality of players has changed ... the manliness of footballers, of that confrontation moment. I don't think it's because they aren't strong characters but they're used to texting each other, to Facebook-ing each other. They're not used to the up-front, real conversation that we are.
"If you turn the music off in a dressing room you'll hardly hear anything. I try to work with it. I get them into groups and tell them to write [issues] down. In my day you'd sit in a room, someone would give an opinion and everyone would join in. Now you might get one; it would be dead quiet."
Initiation … or humiliation by cactus?
The initiation ceremony is the key right of passage into a dressing room. Dyche, Vaughan and Sanchez all agree that having the confidence to take part is good for building character and team spirit.
Modern England rugby debutants have to sing a song - or a rap, in the case of prop Alex Corbisiero - on the team bus after the game.
Back at Wimbledon 25-30 years ago, Sanchez, who scored the winning goal in the 1988 FA Cup final against Liverpool, remembers unsuspecting newcomers being grabbed and stripped naked.
"You had to traipse across the common (where Wimbledon trained) with people walking their dogs, holding your modesty and walk through a transport cafe back to the dressing room.
"There was a mental initiation process as well which you had to get through. Some players in the dressing room were extremely funny, extremely cutting and they could kill you in front of everybody else. You had to get through that and some players didn't make it."
But can initiations go too far? Dawson went on a Barbarians tour to Zimbabwe as a 21-year-old young thruster in 1994, still a year away from his England bow.
"I had my backside spanked by a cactus," he recalls. "I'm bent over a chair with my trousers down by my ankles, with a load of Barbarians and management having a laugh. This cactus is six-foot high with a big two-foot leaf at the end of it.
"And not only that, but my best mate Nick Beale [also of Northampton] had to do it ... he's just pathetically tapping my backside. So Derwyn Jones, the [6ft 10in] Welsh second row, pushed him out of the way and started whacking me. When we went back to our room Nick had to pull the splinters out."
Although disguised as banter in that most macho of sports, it had a profound effect.
"I was embarrassed," Dawson recalls. "I was embarrassed for Nick. What was most disappointing was that I dreamt of playing for the Barbarians more than England. Putting that Baa-Baas shirt on was absolutely incredible because of the players that had been playing in it previously. So to then be in that position, it shattered my dreams of playing for the Barbarians. That's what really hurts, rather than a few splinters."
Each to their own ... or separate rooms
How does a team divvy up its changing area? Dawson, who played for Northampton, Wasps, England and the Lions between 1991 and 2006, remembers rugby dressing rooms divided up according to positions.
"The forwards tend to be in their corner. In the early days it was archetypal physicality; chest bumping and head butting each other, or punching the wall.
"The backs are looking at them thinking 'what a bunch of losers, let's just deal with combing my hair and making sure the shorts are too tight and that I look great'. You'd get the odd spatter of blood … people would be stitched up before they even went on the field."
For Sanchez, friendships were unnecessary within the dressing room. "We were together on the field; we didn't like each other off the field. I famously didn't speak to one team-mate for the last two-and-a-half years I was there, literally didn't speak. As he walked in the room, I walked out. We used to get changed in separate dressing rooms."
Not everyone buys into the team-bonding ethos, even if no-one could question their commitment to the cause. Some characters are natural loners, even those who are leaders on the field.
As England pursued their path to Rugby World Cup glory in Australia in 2003, Jonny Wilkinson kept himself to himself, played his guitar in his room, and learned a new language, French, which would prove useful in his later career at Toulon.
"That's what he did to relax; he wasn't interested in going out for a few beers," Dawson recalls. "People would take the mickey, but not in an offensive way. Sometimes we would go into a hotel foyer with a piano or guitar. We'd go 'Come on Jonny!' And he would go 'No, no, no!'"
Removing the 'assassins' from your midst
Troublemakers, or 'assassins' as Dyche calls them, can destroy team spirit. His philosophy for dealing with them? 'Get in line or you'll be out the door'.
"It is more difficult if you get a group all spraying acid everywhere; that is very challenging. The biggest thing is to talk to them individually, talk to them as a collective - try to make them realise that the group is more important and realign them."
But what about the 'maverick' player who excels on the field, in the glare of the public, but can be a disruptive presence within the confines of the dressing room? Should they be accommodated?
"If they won't realign, hopefully the group will work that out," Dyche says. "It depends; the maverick everyone will have. The maverick who's a bit loose, a bit wild and varied but does the business. The players know that, you know that and he probably knows that.
"The assassin, the 'sapper', they realign or they go, it's as simple as that. If you get too many miserable players, they will find each other and they get drowned in their own misery and they drag everything with them.
"You have to instigate change quickly, and if change is needed where they can't be realigned, then they have to go. You have to find a way - whether it's a loan, they get sold or in some cases, you just have to pay their contract up."
Stop the fight? Or let them get on with it ...
At Wimbledon, fights were a regular occurrence, often during the game. "If we were losing, there would be rows and people being separated at half-time," Sanchez recalls. "At the end of the game no, but at half-time definitely.
"One or two of the managers stayed out of the dressing room for the first five minutes. 'Let them resolve it and then I'll come in and say my piece'. And that was good management. If you've got a dressing room that can resolve it, then let them do it."
If barneys used to be the norm in football dressing rooms, the modern-day footballer is a milder-mannered creature. But fights still break out - "just a consequence of red-blooded males working hard," believes Dyche.
"I've done it myself, and I've immediately apologised," says the Burnley boss, who was captain at several of his clubs. "I've literally pulled them aside, said I was out of order and apologised because my intent was never that. I remember one player who was constantly undermining me, and I pulled him aside and said 'Listen, shall we go outside and have it out? But you catch me with a sly one, I'm coming back every single day.' And that was [the end of] it."
Generally the players step in and stop training-ground rucks themselves. But Dyche remembers an instance where a player wasn't pulling his weight, winding up the rest of the squad. So they decided to 'let him have it'.
"It was someone they thought 'about time'. I thought the same, I thought 'go on' because he'd been giving it all that. I won't tell you who, but he picked on the wrong one."