Shearer felt following Monday night's defeat at West Ham that Newcastle would improve. However, he was left disappointed and took a pop at summer signing Florian Thauvin, who turned up to the game in a tuxedo.
"Before anyone has a pop at me, Watford were absolutely outstanding from start to finish, better all over the park", he said on the BBC's Match of the Day.
"This is a Newcastle team that got absolutely battered from pundits and media alike because of Monday at West Ham, being beaten 2-0.
"They are at home, you'd expect them to come out, roll their sleeves up and have a right good go.
"And I looked at Newcastle there and I thought 'no, no chance'. There wasn't enough there at all.
"He [Thauvin] turns up in a tux. This is a serious business we're in here. It was funny on the first day of the season, it's not funny anymore", the Newcastle legend added.
And Shearer sees big problems for McClaren.
"From start to finish Newcastle were abject, really, really poor and big problems for the manager."