We're talking 17-18 year olds who probably made the decision when they were 16. These are teenagers and 2nd thoughts, doubts and hasty decisions come with the territory. Just saying at that age nothing is final.
To me the LOI is like a good faith reservation, with good and honest decisions. (Adult speak).
Now back to the teenager throw in parent(s), graduation, girlfriend, friends, travel, fear, next phase pressures, etc.., if one thing changes (new coach, new recruit, coaching changes, juniors return, etc.) at the place you made the reservation this will turn a hectic and uncertain future into chaos. In the Spring they have time to rethink.
Perhaps the Miller change in MAL's case tilted the scales. To me it doesn't have to be major, just a change that could sow doubt or affect their confidence in their decision they made.
Just saying they are teenagers after all and picking a school ain't the easiest decision they will make, but perhaps it is the first of many important ones they will be making in their lifetime. The LOI brings certainty, security and allows them to focus on other things (like partying, graduating, video games, girls and other teen stuff).
I think that's why many coaches keep in contact with recruits after signing to get their butts on campus.
