Volume is a factor moving numbers but not nearly as important as where money originates (in other words who bet it). Less volume basically means less money on both sides of a game with perhaps a slight edge going to less money bet on favorites. Bottom line I don't think the numbers offered by the major offshore sportsbooks are affected much at this time because of loss of volume. Mainly because there is still a ton of volume being wagered on the tournament.
I was just thinking maybe more SHARP $$ and little LESS public money currently and could affect a lines as some general public admittedly sits on the sidelines.