One factor in decommits, especially this time of year, is that the player has gotten to where his grades and SAT numbers are well known. The player may be discovering that he does not meet Division I eligibility criteria, or he might clear that (very low) bar yet fall short of what the school's admissions office will countenance. He has to reopen his recruitment, and many times these guys end up at D2, in JuCo, or perhaps betting the ranch on the MLB draft.
The players in those situations are not likely to want to publicize their situations. And the schools are not permitted to comment at all.
I do think that very early commitments fuel this problem. Some of the kids are committing before they get their first high school semester grades, so they may be clueless about where their numbers are headed. (Not to sound mean, but the same kids who make poor grades are the ones who don't pay attention to the need to hit their numbers. We've even had kids who honestly have no idea what their GPA is; we have to get school records to find out what we're dealing with.) On the other side of the deal, the program is assuming they'll pass muster, but later has to deal with what happens if, 2-3 years later, that's not in the cards.