The head of the government’s flow study group – Ira Leifer – told Dan Froomkin:

The lack of accurate information has taken its toll, he said. If BP had properly understood what was going on 5,000 feet below the surface, it never would have attempted to stop it with a “top hat”. And had they realized the pressure from the oil reserves was beyond the threshold for “top kill” they wouldn’t have wasted time on that, either. [While BP and the government originally estimated the leak at 1,000 barrels a day, Leifer said that it may be spilling as much as 100,000 barrels a day.]

“We could have effective containment systems available now, if we’d had the measurements,” he said.

This is unfortunate. Not only did top hat and top kill waste months of time in which BP could have taken effective steps to contain the oil, but top kill probably made the oil spill worse: