I would say Games athlete would be similar to perhaps a world regional Olympic Lifting meet.
According to their Games profile, Froning, Smith, and Fraser have Oly totals varying from 3.25 - 3.63 of their body weight.
In comparison, these ratios would have landed these guys perhaps 19th or 20th out of 20 in the 85kg men's category at the 2016 games.
So yeah, world class would be fare.
Using their games profiles isn't the most accurate way to compare this stuff, but it's the best we've got.
If we compare the 5km run times. (Yeah, I know these are track or road times not off-road, but again the best we've got.)
Of these three, only Smith posts a time of 20:20
Others in the top 5 from the last few years who have a posted a 5km time.
Garard = 17:32
Biley = 19:00
Vellner = 19:18
Gumundsson = 19:20
Hendel = 20:32
Khalipa = 23:20
These guys would fall about halfway down the roster of a typical US high school Senior Year Cross Country team. The 46th Percentile to be exact
So I wouldn't say they wouldn't make the Varsity team, they'd probably do OK. sub 20:00 isn't too bad for a 5km, but it sure aint the sub 15:00 needed to be really competitive.
However, point of order, the Stillman height/weight ratio table says a 5'11" runner should ideally weigh around 75kg, the Games guys are weighing in at around an extra 10-15 kg. Try doing your next meet with 25 lbs strapped to your back.
The Games really is geared more as a Power and Recovery sport, then a true generalist sport, as Crossfit WODs tend to be around the 10-15 minute mark and often shorter, and often incl short breaks, a few seconds to as much as 30-40 sec. long.
If it helps, for comparison the world record for the 5,000m in the Icosathlon is 18:46, not too far off the Games guys average of 19:50.