A verbal offer is one man's promise to another, as is a verbal commitment. It isn't legally binding, but it means a lot more than nothing. I don't think a verbal offer or a verbal commitment is given lightly in baseball (football may be a different story altogether). The vast majority of offers and commitments that I've seen have been honored, with the exceptions being a change of head coach, obvious lack of development of an early recruit, or a kid who was a flake.
Much more common is a poor fit between player and school that results in the kid being cut, never playing, transferring or quitting. Avoiding this mis-step should be where you spend the next couple years of homework. There are lots and lots of great threads (and people) on this site that can help.