A big question is how much moisture does it take to "ruin conditions", as Geoff alluded to. Although the consensus seems to be that it is impractical to control rain water to keep the greens firm consider what happened at the Nationwide Championship at Barona Creek this Nov.
The Super turned off the water to the greens a full week before the Championship to provide the firm conditions that Geoff was alluding to. Those of you who have played Barona will surely agree that for the angles from their wide fairways to work effectively, the greens must be firm, to penalize the inproper approach angle. After watching the first round on TV there was a furor on gca over the softness of the greens. JK even started a thread about how the Nationwide Tour softened conditions to make their guys look good.
Well, the reality of the situation was that each morning there was a fog delay lasting several hours; most unusual for Wild Cat Canyon. That small amount of moisture, deposited early in the morning, was all those guys neded to stick shots at will. So, would tarps have helped this scenario?
By the way, why don't tarps kill the grass on baseball or football fields?