How can the team being heavily favored by the public become less of a favorite in terms of point spread?

This doesn’t happen often, but when it does it’s a sure sign that “smart money” (large wagers by individuals or a syndicate) has been placed on the Underdog.

Smart money can cause the spread to go in the opposite direction of betting percentages. One or two accounts betting the limit at a sportsbook can cause the betting line to move in the opposite direction of what the betting percentages would suggest.