Listen, if a well known and very respected modern orthodox rabbi can cite a figure of 50%, even if it is off it is going to be in the ballpark. Is 50% an overestimate? We don’t have proof either way. It might be an overestimate. It might be an underestimate. Or it might be right on target. But even if it is off, it is not going to be widely off the mark, otherwise it is inconceivable such a highly respected rabbi — who himself is modern orthodox! in one of the largest MO communities in the world! who has a lot of experience with MO families with his rabbinical/pastoral pulpit position, being the rov of a shul with 600 (yes, 600) MO families — would cite the figure.
Rabbi Pruzansky doesn’t need a study to see the extent and magnitude of the problem. He experiences it every day in his line of work.