Great Britain's 60-strong squad head to Moscow from their preparation camp in Spain with a number of their London 2012 stars far from top form.
Olympic heptathlon champion Jessica Ennis-Hill is absent through injury, long jump gold medallist Greg Rutherford travels despite spending six weeks on the sidelines and high jump bronze medallist Robbie Grabarz admits he has struggled to rediscover his 2012 levels.
Olympic champion Mo Farah looks in top shape for his assault on another 5000m and 10000m double but 400m hurdler Perri Shakes Drayton is the only other British athlete to feature in the world's top three in her chosen event.
"I'm not writing off the British team this year, and I don’t think anybody should, but it doesn't surprise me that the athletes that competed so well last year are having a fragile time, it sort of happens like that after an Olympics," said Coe, the vice-president of the International Association of Athletics Federations and chairman of the British Olympic Association.
"The smart athletes triage their four year cycle and my dad always said coaching me the year after the Olympic Games was like coaching an egg shell.
"You know you do go to the well an awful lot of times in an Olympic year, both mentally and physically.
"When you’re in an Olympic year there are no tomorrows, you’re not thinking 'will I do something this year that might infringe on a World Championship down the line', you just live for that moment.
"The year after the Los Angeles Olympics I don’t think I put more than three to four training weeks together without an injury and that was no coincidence.
"It was because of seven races in nine days in LA and the special challenges of an Olympic year."
British athletes won six medals in the Olympic track and field programme in London and claimed seven at the previous year's World Championships in Daegu, including golds for Farah in the 5000m and 400m hurdler Dai Greene.