I think we have the wrong approach here, Whitley is a good player whose game is going to improve with the WC experience. However, it is a somewhat foolhearthy to think that Whitley could 'lock down the opposition midfield'. Whitley is is a good solid tackler and is best when going forward with his penetrating runs.
We all know that the midfield is the engine room, and if we only have one piston (Whitley) firing, then the engine will shut down.
Shutting down the opponent's midfield is a total team effort:
Tight disciplined marking, denying opponents space, cutting off passing lanes
Defending in blocks, with strikers making first tackle
Defence pushing up, keeping middle tight and compact
To suggest one man can do it is very naive, and comparing Whitley to Keane is unfair, they are similar but Whitley is just discovering his game while Keane has already proven himself.
Our midfield play will decide how far we can go in the WC, I've noticed that Beenie has placed a lot of emphasis on midfield, looking for a lefty etc.