I don’t know anything about the recruiting practices at Pomona, but the coaches in the NESCAC are given slots. If your daughter has passed the pre-read at Williams and if the coach has said that he will support your daughter’s application, then the odds of being accepted (if she applies ED) are extremely high.
My son went through the recruiting process last year. As midwestmomofboys suggested in her post, my son asked the coach how many of his supported recruits had been accepted over the years. The coach told my son that 100% of his supported recruits had been accepted. My son applied ED last year and is now a freshman loving everything about Williams.
Good luck to your daughter.