I don't think anyone doubts that we have a good chance of a medal in the mixed 4x4 with our best team out. But that doesn't mean the athletes believe that, or believe that it is worth hurting their individual chances. Maybe they will have a different view going into Paris. But it's clear that these champs were always something of a test event and therefore were always likely to be a relative let down from a GBR point of view.
I mean, just look at the list of people we're missing, all of whom are in the top 3/4 of an event in GBR this season, for one reason or another:
Azu
Hinchliffe
Prescod
Hughes
NMB
MHS
Young
Pattison
Kerr
Wightman
Atkin
Lansiquot
Anning
John
Gill
Muir
KJT (effectively)
That list includes many of both our individual medalists at the last 2 worlds, and many of our prospective relay teams.
Then consider the athletes who might not be quite at their best because they are worried about trials, or who took a casual approach here ie only did one event when they might double in Paris etc.
Finally, we're never going to be a country who wins masses of golds. And even if we put out our top 4 in the mixed, the US would almost certainly still beat it if they did the same.