“I thought he’d come in for a fresh start, especially with talented new players coming in over the summer, but I’m afraid it’s just been car crash,” said Quinn, in an interview with talkSPORT.
“And at the moment, Newcastle have got the wally with the brolly in charge…and the next three or four games will define his tenure.”
The Magpies suffered their fourth consecutive defeat on Wednesday night after Championship side Sheffield Wednesday earned a deserved 1-0 win at St James' Park.
McClaren’s only competitive win as Newcastle boss came against Northampton Town in the League Cup second round last month, and his honeymoon period is now well and truly over.
The Tyneside club were among the highest net spenders in Europe over the summer, but none of their signings - with the exception of Chancel Mbemba – have settled quickly.
Georginio Wijnaldum started the campaign strongly but has since faded, while Florian Thauvin has failed to show any signs of being an upgrade on Remy Cabella.
Aleksandar Mitrovic hasn’t been on the pitch long enough to showcase his talents, but is due to return from suspension this weekend in what could be a timely boost for McClaren.
Despite the woeful start, sacking McClaren would be no guarantee of an upturn in fortunes, with the quality of the Newcastle squad being the real issue.
Too many of the so-called experienced heads – Moussa Sissokko, Cheick Tiote and Fabricio Coloccini, to name just three – have failed to demonstrate they are up for the fight this season, and a new manager is unlikely to change that.