Park can play a little of that role as well. Besides, United don't really play with an out and out defensive midfielder who wouldn't venture into the opponents half the game. Scott Parker's a decent player at what he does, but he wouldn't bring much to the current United or what is lacking at the moment
I see Parker as more similar to Park than Parker to Fletcher. Fletcher's best attribute in my view is his ability to snuff out opponents dangermen. This is why he is regarded by many as a big game player imo, not because of what he brings to the team, but more for what he detracts from our opponents.
I see Parker as more of a Keane (though obviously nowhere near Keane's class) type player, than Fletcher. He is very comfortable in a defensive role and has the ability to carry the ball forward and be an influence offensively.
He has the type of personality that wants to dominate games, and an attitude that refuses to yield when the chips are down. I believe it is this mentality that would make him a very useful player at Utd. I would take Parker in a heart beat, he is a leader and i believe he may surprise a few people on how important he could become to our midfield.
Park shares many of Parker's attributes and look how important he has become. You don't have to be a world beater to become a very important player. Every team needs players like that and i would suggest there have been more than a few away games this season where our midfield would have benefited from someone with the battling qualities and desire of Scott Parker.
-------------VDS-------------
O'Shea---Rio---Vidic----Evra
--------Parker--Carrick------
Valencia-----------------Park
--------------Rooney--------
----------Hernandez---------
Looks pretty solid to me, i personally can't see Arsenal, Liverpool, City, Bolton, WBA, Wolves, Blackpool, Newcastle and Villa dominating that midfield away from home quite so easily.