Mosconi's high run is definitely breakable, but who cares? As many have theorized, Mosconi and the other straight pool greats of the era probably had higher runs in practice.
One thing I'll continue to argue against, though is the idea that the players of today are better than past players, not because I'm one for nostalgia, but because there's is no evidence to support that idea.
Cue sports and their players don't "evolve" like other sports and athletes. We can easily see that Bob Cousy would be no match for Stephen Curry and that if the two hand set shot was used in the modern era it'd get rejected every time, but for cue sports, the only barometer for skill is what you do at the table, and players of the past ran balls just as prolifically as players of today.
And no, equipment wasn't easier and "buckets" weren't used for pockets. As mentioned, they played on 5' x 10's until the 40's, the Ivory balls in use were heavier and a bit bigger, cloth was slow nap (which, contrary to another opinion in this thread, would make straight pool harder, especially considering the balls were heavier. More likely you get stuck in the pack, more clusters to deal with, etc), and pockets were just as tight if not tighter. Pocket from a Greenleaf/Rudolph exhibition:
Someone might say, "Well, ever since Efren arrived, he really changed the game with his kicking. I don't think a past player would have the knowledge to compete, since kicking wasn't used much."
This is also wrong. What makes Efren such a great kicker? The fact he plays carom billiards at a high level. Up until the 50's, carom billiards was a pool player's "2nd game." All those straight pool players of the era played billiards at a high/world class level. Ralph Greenleaf took 3rd in the World 3 Cushion Championship in 1942, when he was already past his prime.
I also like to use Ray Martin's multi-decade career in this argument. in 2011, he cashed in the 14.1 Worlds and beat Oliver Ortmann, a "modern player."
Furthermore, in 1994, at 58, he finished 5th in the WPA World 9 Ball championship. Granted, WPA fields were weaker in those days, since the top pros were playing on the PBTA, but Martin finished ahead of Mika, Warren Kiamco, Oliver Ortmann, Thomas Engert, Ralf Souquet, Bobby Hunter, Morro, Ernesto, and many others.
Sure, fundamentals have gotten better and tighter, but you can change your mechanics if need be. If Mosconi, transported to the present day, was having trouble, he could hire a coach to tweak his game/mechanics, a luxury he didn't have in his era. He might be even better today because of that fact.