A number of prominent Arsenal supporters' groups say "urgent action" is needed to halt the "alarming and desperate state of things" at the club.
In July, they called for owner Stan Kroenke to "reinvigorate" the Gunners.
Arsenal are eighth in the Premier League, eight points adrift of a top-four Champions League qualifying spot.
"It feels like the club is rudderless and floating aimlessly, unsure of its destination," said a statement from the fan groups.
The collective of fans say they are backed by a petition with 120,000 signatures.
Kroenke first invested in Arsenal in 2007 and became majority shareholder in 2011.
The Gunners have not won the league since 2004 and their most recent successes came with FA Cup wins in 2014, 2015 and 2017.
The supporters' groups said that, while issues raised in the July letter "have not gone away, it is the overall alarming and desperate state of things, on and off the pitch, that need urgent action and take precedent amongst our concerns".
They added: "Until the club, especially the senior management structure, is running efficiently, effectively and ambitiously then few other issues can, or will, be satisfactorily resolved.
"The last decade, notwithstanding the FA Cup wins, can legitimately be seen as lost years, both on and off the field, when the team has not only stagnated but actually regressed.
"To date, that is the legacy of the 'Kroenke years'."
BBC Sport has contacted Arsenal for comment about the letter.