This time the concerns seem genuine.
Nothing is ever certain in boxing but if Joseph Parker is, indeed, matched against undefeated Ukrainian heavyweight Andriy Rudenko on the undercard of Alex Leapai's world title shot in Germany in April, Kevin Barry's warning could be spooky.
Before Parker demolished South African veteran Francois Botha last year, Barry voiced his angst at the disparity in experience.
In reality those fears were misplaced.
With a raw and lethal display of power Parker proved Botha was well over the hill.
Rudenko, a member of European boxing giants K2 promotions, is an entirely different prospect.
The 30-year-old is no pushover - he comes forward, has solid defence and likes to pressure his opponents, though his 24-0 record has been manufactured almost exclusively in the Ukraine, only once fighting in Belarus.
Compared to the eight-year pro, Parker is a budding rookie. He produced two explosive knockouts - of Botha and Afa Tatupu - last year and his swift development while training under Barry in Las Vegas has impressed.
But with a 7-0 record there is still much to learn.
"As a trainer I would not take this fight," an agitated Barry said bluntly yesterday. "When was the last time a 7-0 prospect ever fought an eight-year professional fighter with an undefeated 24-0 record? It just doesn't happen.
"This is a huge opportunity for us to go to Europe and fight on a world heavyweight title card and to introduce Joseph Parker to Europe. But there will be other opportunities.
"This is a fight we don't have to take right now."
No contract has yet been inked with Rudenko but Duco Events, Parker's promoters, have been promised the fourth fight - and first on the international broadcast - of what could be a momentous night for two Samoan-Kiwis.
After rocking previously undefeated Russian Denis Boytsov, Leapai will attempt to pull off another shock against world champion Wladimir Klitschko.
For the past month Barry has been scouting footage of Rudenko, though he could only locate two fights from four years ago. He also harbours concerns about getting a fair go from the German judges, pointing to Roy Jones Jr's refusal to fight there throughout his career.
"As a trainer this is not the perfect scenario for me, either," Barry said. "I'm still waiting for a signed contract. I'm not overly excited about this fight.
"We're going to have to knock the guy out to win a decision over there."
As usual, Parker seems unperturbed by his continued fast-tracked progression. After a near two-month spell at home in Auckland, the 22-year-old returns to Vegas on Saturday to prepare for the April 26 showdown with an intensive 10-week training camp.
"For me it may be a risk because he's been a pro for a long time but I know if I put in the work I can be confident," he said.
"We sat down and discussed it as a team. Challenges like this help me lift my game.
"It's still early days. We're moving pretty fast. It's exciting for me to be getting these opportunities. I haven't heard of anyone who's had seven fights and been on a world title card. It's my goal to be champion of the world and these small steps might get me there."
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