The Marathon Man was the stuff (especially with that cast) for a masterpiece. It's a good film though, but somehow still very, very wasted. 6/10
The directing is amazing too.
Really? I don't remember it to be special, I remember that Schlesinger doesn't make much of some scenes which should inspire a director. But I haven't watched it for a zillion years. Maybe I would spot now things i did not care for then, or wasn't able to see.
And of course, Hollywood was almost completely made up of people who refused to stay "on the farm" and escaped to Tinseltown with the hope of gaining fame and fortune. I've never seen the film you've described, but it is obviously another exercise in Bad Faith, a Hollywood specialty.