Last year at this time I said Ollie S, but that's not looking good right now. Not sure what's happened to him. I think Spieth, Day and Rory are gonna be the Big 3 for a while. But I do think Justin Thomas and Matthew F have some potential to get up there with them.
Speaking in practical terms, would it even be possible to make a swing with your foot on the tee marker without moving it? Most tee markers I've seen aren't heavy and bolted down like a bench or a chair would be.
I've played with guys who shot 67 or 68.
I don't know what he shot, but I was playing in the group ahead of Ed Dougherty one day many years ago. He was knocking the flags down all day long. I can't remember how many he stacked inside 10 feet, but it was more than a handful. I remember someone commenting how poor(sarcasticly) one of his shots were that stopped 20 feet from the hole. Most impressive ball striking I've ever seen in person.