Mosconi was a better Straight Pool player than anyone else, including Lassiter. It's doubtful that Lassiter in his prime (yes he played great in the 1950's) would want to play a long Challenge match against Willie with big money on the line. If Crane and Caras couldn't beat him, what chance would Lassiter have had? He would have been a big underdog. And I have a lot of respect for Luther. He was acknowledged as the best 9-Ball player of his era and he became one of (if not #1) the top 14.1 players after Willie retired. His chief competition coming from Joe Balsis, Irving Crane (who had not yet retired), Cicero Murphy and Harold Worst. Jimmy Caras came out of a near ten year retirement to win the U.S. Open Straight Pool title in 1967. He was 57 at the time.
It's true that Willie didn't care for gambling. He felt that as the most well known player of his era he should keep a squeaky clean image and he did just that throughout his career. But if he had been pushed to play a challenge match for big money, I don't doubt for a second that he would have accepted the bet. I don't think anyone was too anxious to put up any money to see if their horse could beat Willie, for good reason. Willie was all about the money and he truly believed that no one could beat him. He proved that to be true many times over the course of twenty plus years.
Most of these players, of any games, at best played three shots ahead of the current shot. To compete with Mosconi, they would have been playing with the man who shot a minimum of six or seven shots ahead at all times. If the break shot freely spread all balls open, then he would play all fourteen shots to the next break shot. Mosconi said no one could control where all of the balls on a break shot would roll to. But, people still wonder why he could move so quickly from shot to shot. It was because he was playing so far ahead of the current shot, that he infrequently had to reset the runout to the next break ball. He couldn’t control where all the balls were going on a break shot, but he knew what the balls weren’t going to do from his controlled break shots. He would still roll over today’s current 14.1 players.