Scarlets head coach Wayne Pivac says the Pro12 league should not be judged on this year's failure to provide any Champions Cup quarter-finalists.
Only English and French sides have made the last eight of the competition in 2016, but Pivac feels it is a one-off.
"The standard is down - I put that down to significant injuries to significant players," he told BBC Wales.
Meanwhile, Wales full-back Liam Williams could return for Scarlets at Connacht in Saturday's Pro12 clash.
Williams will make his comeback from a foot injury if he comes through national squad training.
He is one of the players whose absence Pivac highlighted, in explaining the Champions Cup exit of all the Celtic nations.
"It's World Cup year, it's a one-off year, and it's better to judge the competition in the years outside a Rugby World Cup," New Zealander Pivac added.
"(The Irish) had significant injuries as well, it's got to take a toll."
Capitalising on Test weeks
Pivac's team were winless in Pool 3 in Europe's top tier with Racing 92, Northampton and Glasgow registering doubles over them.
But they are out to repeat the Pro12 success they enjoyed during the World Cup, as they approach more games without their Six Nations stars.
The Scarlets still top the table despite a drop-off in results, having beaten Connacht 21-19 at home in their most recent league game.
"We want to remain as high up the table as we can," said Pivac.
"There are eight or nine sides going for six slots (in the Champions Cup next year), some quality teams are going to miss out."
Scotland flanker John Barclay has failed to recover from an arm injury while five other Wales squad players are unavailable for the Galway game.
Centre Gareth Owen, prop Pete Edwards and back-rower Rory Pitman are fit again after missing the Champions Cup defeat by Northampton through injury.
Flanker James Davies may return from a foot injury in their subsequent game against Edinburgh on 12 February.
Meanwhile Samoan lock Maselino Paulino will leave for a French club at the end of his short-term contract this season.