He is quick.
But he 's role priority need saving enegry to defend.
His position need he stay at middle area to protect the middle important route,
so he don't run around like the other position. He need positioning at middle and stay at this area to guard, not the front.
He need stay the energy to run all what he need to run and defend.
If he don't take the role of defensive middle field (DMF),
he don't need take more responsibililty of defend,
he don't need save more enegry also.
If he be a attackive role, e.g. Silva 's position, then he can use most of enegry to run around and fast running.
But he 's role priority need saving enegry to defend.
His position need he stay at middle area to protect the middle important route,
so he don't run around like the other position. He need positioning at middle and stay at this area to guard, not the front.
He need stay the energy to run all what he need to run and defend.
If he don't take the role of defensive middle field (DMF),
he don't need take more responsibililty of defend,
he don't need save more enegry also.
If he be a attackive role, e.g. Silva 's position, then he can use most of enegry to run around and fast running.