Shearer wrote in The Sun: "I know people will say it is harsh to judge so soon in a new season. I agree.
"Yet the thing is we are really judging Villas-Boas from his ill-fated spell in charge at Chelsea.
"It didn't work there and, so far, it's not working at Tottenham either.
"Their performance against Norwich on Saturday will have set some alarm bells ringing.
"While the Canaries equaliser came late on, it was thoroughly deserved.
"In fact, they deserved the win and but for some incredible saves from Brad Friedel they would have had it.
"A Spurs team that played with so much width and imagination last season just seemed to be lumping the ball up to Jermain Defoe. And he's no target man.
"If you are going to do that you surely play Emmanuel Adebayor - not start with him on the bench."