Gary Neville: I had my spats with Fergie but he would never criticise a player in public like John Carver
It rarely works when a manager lets his emotions take over. These things should always be kept in the dressing room
When a manager publicly criticises his team or singles out individuals with the kind of devastating condemnation that Newcastle defender Mike Williamson suffered from John Carver last Saturday, it is usually motivated by one of two reasons.
In the first instance, the manager will have absolute control of his squad and be comfortable in the knowledge that his actions will be supported by the directors, players and supporters.
He will know that, by taking such drastic action, everybody who matters at the club will believe him to be right because his authority has made him untouchable.
But the only other time a manager will do it is when he feels he has nothing to lose and, in my opinion, that is the reason John Carver reacted as he did following Newcastle's defeat at Leicester City a week ago.
It was as though he believed his players were trying to take him down, so his reaction was to take them down with him.
In recent weeks, the performances of Newcastle's players have been so bad that Carver must have felt he had to get everything off his chest. The Newcastle squad isn't a group of players you would trust.
But to make such damning accusations against your own players, by suggesting Williamson deliberately got himself sent off in order to miss two crucial games in the club's survival battle, is a high-risk strategy because, make no mistake, the players would react with absolute disdain.
The view among the players would be "That's him done", "I can't play for this guy", and "How can we trust him when he hangs us out to dry like that?"
Tim Sherwood gave a similarly brutal public assessment of his Tottenham players last season following a 4-0 defeat at Chelsea and he was probably in the same position as Carver, feeling that he would not be in charge for much longer and that he had nothing to lose by hammering his players.
He accused them of lacking "guts and character" and did not hide his anger, but stopped short of singling out individuals as Carver did with Williamson. That is a pretty dark place to go, because the manager must think seriously about the impact on the player and his team-mates.
In my time at Manchester United, there were a couple of occasions when I fell foul of Sir Alex Ferguson and one of them was the closest I ever saw him go to criticising his players in public.
It was a defeat against Manchester City in the final derby at Maine Road in November 2002, when I gave a goal away after being dispossessed by Shaun Goater.
We went on to lose 3-1, our first defeat against City for 13 years, and Sir Alex tore into us in the dressing room and said he was tempted to let our fans in so that they could express their anger and disappointment at us.
He then repeated it in the press conference after the game, but he had complete control and authority at Old Trafford and was in a different position to Carver and Sherwood. And as a group of players, we were a strong, successful squad who wanted to put things right because we had been embarrassed.
But Sir Alex would rarely criticise a player in public. Instead, he would take action behind closed doors and leave the public and media guessing.
He left me out of the team for two weeks after I had a spat with him during a Champions League game at Lille in 2007, but it was done privately, without him giving an explanation of my subsequent absence from the team to anybody outside the club. Sir Alex was always in control, but Carver comes across as an emotional person and, while supporters will identify with his positive emotion for Newcastle, that can also become a negative which can colour judgment and decision-making.
It is a difficult balance to achieve. When I played under Kevin Keegan with England, his emotion and passion were seen as incredibly positive qualities at the start of his reign but, by the end, they were held against him as negative factors.
Sven-Goran Eriksson went the opposite way: early on, his cool, methodical approach was seen as a positive, but when the tide turned he was accused of lacking passion and fight.
Some people love the passion of Diego Simeone and Jose Mourinho, but when they cross the line, it becomes a negative.
And already this season, Louis van Gaal has been criticised on occasions by Manchester United supporters for staying rooted to the dugout and not getting involved on the touchline during poor performances. However, in victories against Tottenham, Liverpool and Manchester City, he looked like an authoritative, calm presence.
One of the key lessons you learn on management and coaching courses is the importance of controlled emotion in high-level sport.
I have not been a manager, but from working with Roy Hodgson with England, I have seen the value of taking the emotion out of situations such as half-time team-talks and ensuring that the right message is delivered to the outside world after the game.
At half-time, the temptation of a manager may be to blow his lid with the players but, with England, Roy will have a period with his coaches for three or four minutes - during which everyone can calm down - and control the information that needs to be given to the players.
It is designed to take the emotion out of the situation in order to ensure that clear heads and minds deliver the key points in a cool and calm manner.
The same applies at the end of the game, when a manager needs to spend 5-10 minutes with his press officer to discuss what he wants to say and also be briefed on what he may be asked.
A strong, experienced press officer who doesn't just present the problems but assists with the solution is critical in that immediate post-match situation. Carver needed this last weekend even though he may have gone rogue.
They were clearly not off-the-cuff remarks about the Newcastle defender because Carver repeated them to the newspapers after initially telling television reporters that he believed Williamson had been sent off deliberately.
It was interesting to hear Carver reveal on Thursday that he and Williamson had discussed the matter, shaken hands on it and put it behind them.
Carver also said that he had "maybe learnt my lesson", but we will only discover the full impact of last week's comments once Newcastle have played their final three games of this season.
In many respects, what he did at Leicester was managerial madness, but Carver's outburst might ultimately prove to be the moment that halted Newcastle's slide down the table and acted as the catalyst that could keep them up.
Whether it was a calculated gamble on Carver's part or nothing more than his frustrations and emotions boiling over, it will have focused minds among the players.
There were times at United when we, as players, would get together when results were going against us and resolve to put things right as a group.
The Newcastle players had their meeting last Sunday after Carver's comments would have angered them, and they will have emerged a stronger and more determined squad.
But Carver is an emotional manager and Newcastle is a very emotional club, with the managerial appointments of Keegan (twice) and Alan Shearer highlighting how decisions have often been made at St James' Park.
When emotion is allowed to play a part in any decision, it very rarely goes well and time will tell as to whether Carver's actions last Saturday were a huge mistake or the managerial masterstroke that gets Newcastle over the line at the end of the season. (© Daily Telegraph, London)