Archer, Mills, Woodward, Deuel , Hatch, Oscar --- the guys who nearly never are among the last few in premier nine foot table events in America in 2014 or 2015. These guys aren't typically found in the last stages of Derby City, Turning Stone or the US Open 9-ball. Stepping up in competition is not what these guys need, although I feel confident Skyler Woodward will be a great player within a few years. Still, in rotation games, his track record on nine foot tables is pretty mediocre to date.
Rodney still has a strong top gear, occasionally strong enough to compete with the most elite internationals.
Justin Bergman had a major win against an elite international field at Hard Times in 2014, so there's at least some evidence he might be up to competition at the most elite level.
Of those you list, the only one I think would fare well in international competition is Justin Hall, 7th in the 2014 US Open 9-ball, 2nd at the US Open 10-ball, and 5th at the last Turning Stone event. Add his prodigious skills in both banks and one pocket and you've got a crazy-talented player capable of great things if he chose to get some international seasoning.
Face it, the US has just two players capable of shining at the highest level of international competition. Once you get past Shane and Mike, it's a steep drop to the rest of the American talent pool, possibly excepting Hall.
I really have to wonder what you're watching to conclude that so many of the guys who have been unsuccessful on American soil would find sudden success if they tried their luck against even tougher fields than they are used to.
The worst thing we American pool fans can do is be satisfied with what we've got. The place American pool pros hold in international competition is embarrassing, and when our guys try the WPA events, they have a poor track record of late. This can change, but if it changes, it will be the young guys who make it change, not the past-their-prime members of the old guard of American pool.