This is a very silly argument, amounting to "Runners have cheated since time immemorial, so now that we have the technology to tell definitively when they've cheated, we should make cheating legal." The solution is obvious: instruct runners to maintain better contact with the bases when the ball is anywhere near them. If this means a slower jump on tag-up plays, or more runners called out trying to steal, then that's what it means. End of discussion, no? I didn't say they were cheating. Villar wasn't cheating on that slide. I'm saying that if you slide straight into a base and right over it, and only a close examination with a high-speed camera can show that his upper body came off the ground a millisecond before his lower body reached the bag, then maybe it's not worth making that examination. Maybe if the umpire had been lying flat on the ground with a good view of Villar's belly he might have caught it. But he was in perfect position and he didn't. A tag-up play is a completely different situation. It's hard to call, because you have to assess two things happening hundreds of feet apart. But it's not impossible. And umpires almost always get them right. We've gotten into the territory of trying to judge whether a horse's feet are all on the ground at the same time, or whether urine flows in a continuous stream or a collection of droplets. Interesting questions, but nothing to do with how the game is played.