Oklahoma State ranks 11th in defensive field goal percentage and 39th in scoring defense. Texas Tech is known for its stingy defense under coach Chris Beard, one of the best coaches in the country. 
But there is more than just two outstanding defenses going here that should make this go Under the total. 
Texas Tech has faced very few strong defensive teams.The Red Raiders have had a tough time going up against opponents who primarily play zone defense, which is the style Oklahoma State uses.