Dictating the tempo of play.

What would you consider the main important attributes in someone who is able to effectively dictate the tempo of a game. I've noticed that it seems to help if they're not overly fast as you then have to develop a different game. Passing, creativity and decisions is obvious. Anticipation? Flair? First touch? Also what would you think are the ideal phyiscal attributes.

Composure and Concentration, Off the Ball, Teamwork as well as those you mentioned. Strength so that he is not so easy to muscle off.

I would add Aggression and Work Rate as you will want your regista to impose himself in the midfield and constantly involve himself in play. Of course, high levels of both will require Stamina to keep him from running out of steam.

I wouldn't put much focus on Flair. For the purposes of a deep-lying midfielder, high creative freedom will serve the same function.

I was looking for a player whom could rotate with Steven Gerrard in a MC/PM role and control the tempo (yeah, a mean feat I know) but I managed to discover this player and his attributes speak for themselves:

He's been outstanding, and watching his passing, control, composure and creativity reminds me off a Paul Scholes type player minus the long shot ability. The biggest and most surprising aspect was he only cost £3m! He also plays the deep PM DM role very well, in the style of Xabi Alonso.

According to http://www.guidetofootballmanager.com:

Dictates tempo

Will use his intelligence to determine the tempo of the game, regardless of the tempo set in team instructions and his creative freedom instruction.

Requires: excellent Creativity and Decisions.

A must for highly intelligent playmakers. Should be unlearned by players without the required attributes.