Paul McLean admitted no one deserved pass marks as Brechin produced their worst performance of the season at Airdrie.
The 24-year-old refused to gloss over City’s dismal display at New Broomfield, with Ray McKinnon’s side dropping to fifth place in the League One table.
Goals from Scott Fraser, David Proctor, Jim Lister and Nathan Blockley clinched a first home win of the season for the Diamonds.
McLean agreed Brechin deserved nothing from the game and was frustrated they couldn’t build on last weekend’s excellent 3-1 victory over Morton.
He said: “It was a bad day at the office. Things didn’t go to plan and the early goal killed us. We just never recovered from that.
“We were really flat and will have to try and put this result behind us.”
McLean added: “But we just didn’t look like scoring, which hasn’t been like us. This was 100% our worst performance of the season.
“All of the players know that it wasn’t good enough. I don’t think anybody is coming away with pass marks.”
Airdrie took the lead in the second minute when on-loan Dundee United kid Fraser curled a free-kick from the right-hand side through a forest of players and into the far corner of the net.
The 19-year-old midfielder then continued a debut to remember by helping the hosts double their advantage in the 20th minute.
Fraser’s corner found Lister, whose header was tipped against the bar by keeper Graeme Smith, but Proctor knocked in the rebound from close range.
City were on the back foot with Gary Fusco clearing a deflected Ben Richards-Everton shot off the line before Smith brilliantly saved from Blockley.
It was one-way traffic in the second half, and Airdrie made it 3-0 through Lister after good work down the right flank by Chris O’Neil and Keigan Parker.
Brechin were just desperate for the final whistle but there was still time for Blockley to chip a 25-yard shot in off the underside of the bar.
Boss McKinnon said: “I didn’t see any positives for us out there. We were looking for a spark in the second half but never got it.
“This performance has taken me by surprise,” he added.
In contrast, Diamonds boss Gary Bollan declared: “This is where our season starts it’s up to us to build on this.”