By Don Howe
Former Arsenal and England coach
The trend for using the 4-5-1 formation in the Premiership this season is simply explained.
Chelsea's three front men make a successful blend
It is the old story of copying successful systems and successful teams.
Whether it is the World Cup, the Premiership or La Liga, coaches will always emulate formations that work.
So if, as we had in the last World Cup, you have a team like Brazil who played 4-3-3 and adapted their tactics around Ronaldo, Ronaldinho and Rivaldo, people will naturally follow.
If you then get a team like Bolton or Chelsea introducing the same formation, others will look at tapes and adapt accordingly.
The problem is that they will copy the formation without having the players to do it well.
Other Premiership teams have not got Hernan Crespo or Didier Drogba, Arjen Robben and Damien Duff - let alone the three Rs from Brazil.
The 4-3-3 does not actually differ that much from 4-5-1 formation.
In theory, if you have got the players to play 4-3-3 then you are getting three good players forward with a lot more strength in midfield.
But if the wingers or front players play deep, you effectively change 4-3-3, which is an attacking formation, into 4-5-1, a defensive one.
And with one striker you often find him isolated. That is why teams are not scoring.
Teams have to think about the service to a front man to keep him involved for 90 minutes.
If they expect the front player to be a target man or someone to run in behind the defence, then he will become tired very quickly.
They need to ask: "When do they want him to come into the game?"
Ronaldinho is part of a potent front three for Barcelona and Brazil
Good teams like Chelsea and Barcelona do not involve their front man until the middle third of play.
Barcelona last season are an excellent example of a team playing with three front players. They had Samuel Eto'o up front with Ronaldinho and Ludovic Giuly playing either side of him.
There is no way that Barcelona played defensively and they were masters at bringing Eto'o into play at the right times.
The other thing to consider is that other coaches will look at Chelsea's formation and say that they have to match the numbers.
If you have got Claude Makelele, Frank Lampard and Michael Essien facing you in midfield and you have only got two central midfielders, they will start to control the game because they have a extra man.
That is the reason why Manchester United have got three in central midfield.
It used to be Roy Keane and Paul Scholes, but now you have Darren Fletcher too. If you change the midfield, it is going to have an affect on your front players.
You cannot play two up so you might play three forward players, that means one of the strikers might pull wide.
Wayne Rooney played wide left against Arsenal in the FA Cup final last year and he got the man of the match award!
Now people are saying that he does not like it, but that is just trying to find an excuse for his behaviour.
Brazil, Barcelona and Chelsea have been successful with three attacking players, but other teams cannot match them for talent in those areas.
The problems lie in trying to adapt existing players to play in a certain way.
Whether people like it or not, this is the future of football.
But to turn 4-5-1 into 4-3-3 succesfully, you need the right men for the job.