Former Wales captain Gwyn Jones says the Ospreys should change coach Sean Holley, following their 18-11 Magners League semi-final defeat at Munster.
Despite the relatively close scoreline, the Ospreys had just 28% territory and 45% possession at Thomond Park.
"Sean Holley, they have to say now: 'thanks for your service but it's time for you to go'," Jones told S4C's Y Clwb Rygbi show after the match.
"Their three-quarters - five Lions - are disastrous. They create nothing."
The Ospreys were asked by BBC Sport Wales to respond to Jones' strong views but have so far declined to comment.
The Welsh region were only able to field two of their British and Irish Lions tourists in their backline against Munster - Ireland's Tommy Bowe and James Hook.
Hook was playing his last game for the Ospreys before leaving to join French side Perpignan, but he lasted just 39 minutes before a shoulder injury saw him replaced at centre by Ashley Beck.
The Ospreys have opted for Dan Biggar at fly-half in a backline that at full strength has the likes of Bowe, Hook - whose preferred position is at stand-off - Shane Williams, Lee Byrne and Mike Phillips.
Johnson has previously stated that the buck stops with him, while chief operations officer Andrew Hore, who was previously the elite performance director, is also part of the Ospreys hierarchy.
But respected rugby pundit Jones believes that Holley is the man ultimitely responsible for the Ospreys' lacklustre performances on the field this season.
"He's responsible for Biggar staying as their fly-half and as their most influential player, and that Hook hasn't been given a chance," Jones added.
"They have to answer those questions. He's been there long enough and they're not achieving.
"Attacking-wise they are awful. You have to draw the line sometime and say thanks, time to move on."
Holley took over as acting head coach in June 2008 following the departure of Lyn Jones, but was not confirmed in the post until January 2009 when former Wales caretaker coach Johnson arrived as director of rugby.
Some rebuilding work of the playing squad has already begun with the recruitment of back-row pair Joe Bearman, from Newport Gwent Dragons, and Samoa international George Stowers, from London Irish, plus Samoa half-back Kahn Fotuali'i from Crusaders.
Wales record try scorer Williams has also agreed a new deal, as has captain Alun Wyn Jones, while his fellow wing Richard Fussell has flourished this season after joing from the Dragons the previous year.
Another plus has been the emergence of young breakaway forward Justin Tipuric, whose growing maturity has seen him captain the Ospreys on occasion.
But the Ospreys will rue surrendering the Magners League crown they won away to Leinster last year and the matches that got away from them.
In the league they lost home and away to the Dragons, supposedly the weakest of the four Welsh regions, drew against Cardiff Blues at home and also lost at the Liberty Stadium to Munster - before the men from Limerick ended their season in the play-off semi-final on Saturday.
The Heineken Cup is also a story of what might have been.
Poor decision-making at crucial moments threw away winning positions in Toulon and again at Munster.
The Ospreys' realistic hopes of a quarter-final spot were then ended with a loss away to a London Irish side that came into the game on the back of 10 successive defeats.