The Linking Midfielder must be technically proficient and capable of playing with an extreme economy and efficiency of touches. One or two touch play is often the norm. The quality of those touches is vitally important as the linking midfielder must be able to distribute the ball with great accuracy.
Tactically the linking midfielder is a screening player in front of the center backs when his team is without the ball. He should be the teams organizer and communicator. There must be a deep understanding of the different types of defending as they apply to each positional unit and when, where and how to apply or direct application of pressure on the ball.
In the transitional phase of moving from defending to attack it is critical that he possess an understanding of the teams system of play and be a 360 degree player.. He must be able and willing to properly prepare to play the ball at all times while actively seeking the ball. The linking midfielder must possess great game intelligence and a high quality of decision making ability. Creating and changing the rhythm or tempo of the game and understanding when it is necessary to do so are critical weapons for the linking midfielder's repertoire. Distribution or passing skills must be among the very best on the team.
From a physical standpoint the linking midfielder must demonstrate coordination with and without the ball. He should be agile and possess the ability to change pace effectively. He needs to possess strength on the ball and a willingness to challenge opponents in all three phases of the game.
It is the psychological aspects of the linking midfielder that really define the position. Because he is the hub of the team wheel, a 360 degree layer, he must be disciplined, responsible and very poised. The degree of calmness and confidence that he plays with will go a long ways to determining that of his team as well. He must be emotionally stable - never to high, never too low - and remain even keeled whether the game be tied or he finds his team winning or losing. Composure is of the utmost importance. With the goalkeeper, the linking mid is the teams authority on the pitch - an extension of the coach.
Putting it all together.
The primary responsibilities for the linking midfielder are to protect the center backs and to be a link between the backs and the attackers. In this sense he must be a pivot or 360 degree player. Establishing the teams pace and the games rhythm are critical elements of the linking midfielders responsibilities. This occurs on both sides of the ball and in all phases of the game.
Because the linking midfielder will remain centrally located on the pitch and within his teams shape a majority of time he must be able to play competently and confidently facing in any direction. Game intelligence and awareness are essential to his ability to communicate with teammates, organize team shape and direct both the defending and attacking play.
My team refers to the linking midfielder as the Michael Bradley role. Given Bradley's move to an attacking midfielder position in the World Cup this is a bit misleading now, but the idea remains the same. In defending the LM plays advanced of and between the center backs in a protective screening manner. In the attack he often plays between the center backs presenting a back three and allowing the outside defenders to move into the attack. However, he makes calculated and dangerous runs forward to become directly involved in the attacking phase via his distributions or shots on goal.
For more on the Linking Midfielder and his role in the modern game please see Position #6 the Holding or Defensive Midfielder and Evolution in Soccer - the Linking Midfielder.