There is nothing out there worth trading their prospects for. Quintana, Gray, Teheran, and Verlander are not worth the price. They have several pitchers on their farm that can keep this franchise going for years after Keuchel and McCullers eventually go for their big contracts down the line. Morton, Keuchel, and McHugh are going to be well rested come playoff time. If anything, they might need to get a reliever or two, since their bullpen has been gassed for the last month.
Unless Bumgarner or deGrom become available, the Astros just need to stand pat.