In a war between players and the manager, the latter will lose. Managers need the results, and they depend on the players to get them. But players can cost them their job, simply by underperforming on the pitch.
Diego Costa had scored just three goals for Chelsea since the start of the season under Jose Mourinho. He sulked when he was dropped and even threw his vest at the Portuguese when he was an unused substitute against Tottenham last month.
But less than 10 days after the manager's dismissal, the Spanish striker was miraculously back in top form when he netted a brace in their 2-2 draw with Watford on Boxing Day.
That the player looked much sharper since Mourinho's departure suggests that some in the squad had deliberately dragged Mourinho down.
Mourinho had accused the players of betrayal, following their 1-2 loss to Leicester City in his final game in charge.
Besides Costa, several off-form team-mates like Cesc Fabregas and Eden Hazard were singled out by fans and the British media as the culprits who had stopped playing for the manager.
I saw how some team-mates would not always agree with training styles and playing tactics. Even good players would question among themselves: "Why must we train more than an hour? Why do we need running sessions after our training sessions? Why do we play the 4-4-2 formation?"
With Mourinho out of the way and the players showing renewed energy and focus, I can imagine how Costa must be smiling now that the Special One is gone.
In a way, he has the last laugh.
It is easier to replace the manager than to replace a set of unhappy players. Perhaps this has made managers more vulnerable than their players.
Players can complain about their managers and underperform, yet escape the chop. This is sometimes not fair to the coaches but it is now a fact of life in professional football all over the world.
I played under many different coaches and I saw how some team-mates would not always agree with training styles and playing tactics.
Even good players would question among themselves: "Why must we train more than an hour? Why do we need running sessions after our training sessions? Why do we play the 4-4-2 formation?"
Only Alex Ferguson and Arsene Wenger have been able to command total respect from their players in the EPL.
So many players clashed with Ferguson - Roy Keane, David Beckham, Ruud van Nistelrooy and Jaap Stam, for example. But it was the boss who always won.
Unfortunately, this is not always the case today, where EPL clubs want instant success.
In the post-Ferguson era, cracks have started to show within Manchester United.
When captain Wayne Rooney is put on the bench, you know that things are not well in the dressing room. You could see that some of the players are not comfortable and they are just waiting for Louis van Gaal to leave.
It does not help that sitting next to van Gaal with one eye on the coaching seat is Old Trafford faithful Ryan Giggs, who played alongside Rooney.
Perhaps, Rooney is hoping for Giggs to take over.
The striker has a strong influence in the dressing room and by the time you read this, the manager could have been sacked if the Red Devils lose to Chelsea.
And if Rooney starts to score after the Dutchman leaves, then it is hard not to believe that player power was a cause for van Gaal's departure.