I did some of the math for fun. Not including all the extraneous variables and keeping it simple (assuming independence, etc.), the odds of the Astros getting a no hitter through 7 innings alone (which is I think what happened) is the product of the probabilities of each of their pitchers involved getting an out raised to the number of outs each of them pitched. Looks like there were 6 Astros pitchers involved since the 3rd inning and 21 outs, so searching their career IP and H stats (which obviously includes stats from that game to now) the probability that they would combine to get a no hitter through 7 innings would be roughly 0.2%. Or something like that.