There is a general misconception that grooved runways are always better than other surface treatments under wet conditions. A surface with large aggregate asphalt will have the same runway friction characteristics on wet/flooded surfaces as a grooved surface with the same average macrotexture. There are examples of overruns on wet, grooved runways. If grooved runways are not maintained well, or the depth and spacing is as such that the average macrotexture is still low, they will not help you getting better friction on a wet surface.