In the just over three years that Jose Mourinho spent in the Premier League first time around, he was unafraid to row and play mind games with his rivals, be it Rafa Benitez or Arsene Wenger.
The one exception, of course, was the Manchester United manager, Sir Alex Ferguson.
And as we've been reminded time and again, David Moyes is no Sir Alex. Which explains why the Chelsea manager hasn't shied away from the kind of needle that was unthinkable when the man from Govan was in charge at Old Trafford. You saw it in the open way he talked about Chelsea's efforts to sign Wayne Rooney last summer. A manager talking freely about a player under contract with another team is extremely rare and would have been unthinkable in the Sir Alex era.
Now? It's par for the course, to the point that Mourinho went back to it on Friday, 48 hours before today's clash between Chelsea and United at Stamford Bridge.
"I think maybe they will try to sell [Rooney] to a non-direct rival," he said. "They made it clear [that they would not sell] domestically."
Moyes had no choice but to deny they would sell in the summer, while adding: "Everbyody has their own style. I wouldn't talk about other managers or players at other clubs. I can't tell you [Mourinho's basis for saying it] but only time will give you the answer about Wayne. The club will deal with the contract. They will do all the things they need to do, no question."
The point here, though, isn't so much to what degree Mourinho's words will unsettle Rooney (they won't, he knows the situation) or, indeed, Moyes (they're not going to change how he handles his striker).
Rather, it's about the ease with which the Chelsea boss - when necessary - breaks unwritten rules. The substance of what he said was unremarkable - United may sell if Rooney doesn't renew his deal and, if they do, they'll do it abroad - it was the circumstances and the delivery that mattered. At best, it serves the purpose of getting into the opposition's heads. At worst, it shows Mourinho to be fearless in the face of convention and ensures we talk about this rather than his team selection, January transfers or the state of mind of Juan Mata and David Luiz.
Rooney is an issue for Moyes. In less than a year's time, he'll be free to sign a pre-contract with another club, enabling him to leave Old Trafford for no fee. Plus, he's injured, the club's out-of- the-box notion of sending him to Egypt for warm-weather training to aid his recovery from a groin strain having backfired. This delays contract decisions further and, of course, with every week that passes, the club runs the risk of drifting further away from the Champions League places which, in turn, weakens its negotiating position.
The problem for Moyes is that Rooney is just one of many issues that need resolving. Do you extend Patrice Evra's stay for another season or pursue a left-back? When will Robin van Persie be back and what condition will he be in? Do you try to get Nemanja Vidic - a free agent in the summer - to stick around? Where should Shinji Kagawa feature: wide, centrally or on the bench? Is there any way to get Marouane Fellaini to contribute? What happened to Javier Hernandez's mojo? Should Nani, fresh off his mega five-year contract extension, ever get on the pitch? Which of the younger players - Rafael, Fabio, Tom Cleverley, Chris Smalling, Phil Jones - are worth persevering with?
And all that is in addition to the pressure of trying to achieve a top-four finish and do something worthwhile in the Champions League. Faced with this, a bit of needle from Mourinho - and the knowledge that just because he's in Sir Alex's chair doesn't mean he'll get the kid glove treatment - isn't going to faze Moyes.
Nicola Cortese's story at Southampton could be a paradigm for how some find it tricky to evaluate the work of football chairmen. When Markus Liebherr put him in charge of Southampton and they were promoted to the Championship, he was praised. When he sacked Alan Pardew, he was a meddling, interfering boss, a non-football man who should have left it to those who understood the game. When Nigel Adkins, Pardew's replacement, took them into the Premier League, he was praised again, for having the nous to elevate a manager from Scunthorpe. And when he dispatched Adkins, he was the bad guy again, sacking a man who was undefeated in seven matches and had just fought back from an 0-2 deficit to snatch a point at Stamford Bridge. Then, Mauricio Pochettino, the new manager, took Southampton into the top half of the table, playing some sparkling football and fielding a number of home-grown players, some of whom were called up to the England squad; Cortese was good again.
See where this is going? Now that Cortese has resigned from his post, ostensibly because the owner - Katarina Liebherr, who inherited the club after her father's death - wants to sell up, is he good or bad?
Sadly, too many have simply nailed their colours to one mast, depending on who they have access to. Some depict Cortese as an arrogant egomaniac, who took over a club destined to rise again anyway, spent a wealthy man's money and pushed managers out of the way so he could be the star.
Others have lionised him as the out-of-the-box thinker (and, to be fair, it takes some courage to stand up to the group-think - some of it puerile and ignorant - of a certain type of manager) who guided the club on an ever-upward trend and who was undermined by a woman who was failing to fulfill her dead father's wishes.
Obviously the truth lies somewhere in between. What is rather curious here is why Cortese did not simply go and seek a buyer who would keep him on as executive chairman. After all, it was no secret that Katarina wanted to sell.
It's still possible that Cortese will link up with some billionaire (after all, he knows plenty of them from his previous life as a Swiss banker) and return to the club. But, in the meantime, failing to take Katarina and her wishes seriously enough to do something about it has perhaps been his biggest shortcoming.