Uhm I think the maximum value is 1, but you should experiment with values in the range of 0.25-0.5. The higher it is, the more it will break up and the more rough will form. This really only makes a difference in 2-5 day matches.
EDIT: the rough will make the ball misbehave, so you'll get some balls shooting through along the ground, some jumping off the pitch, depending on the crack the ball might seam or spin a LOT more, etc.[DOUBLEPOST=1425138928][/DOUBLEPOST]Currently my to-do list is just to get through all the bugs and fixes first. Then I need to start working on model and animation importers and possibly other small things like being able to break the stumps or send them cartwheeling, etc.