You need to understand that when he says a given fish is 2", that means MOST of the 200 fish he has are approximately 2". By the time he gets to the end of a spawn, he may have a greater number of smaller fish left (especially when people are trying to get him to pick put males, which at that size are usually just guesses and the larger fish).
I guarantee you he isn't putting the fish on a ruler, but if you're buying from him it's because you're willing to pay for quality, not exact size.
I always ask for a mix of sizes in an effort to get some females.