Shearer wrote in The Sun: "Embarrassing, gutless, clueless but most of all very, very worrying.
"Newcastle fans can throw in their own adjectives if there are better ones to describe what they witnessed at St James' Park late on Saturday afternoon.
"A 6-0 trouncing by Liverpool - the club's worst home defeat since 1925.
"You can be excused a bad day at the office.
"But, for the second home game running, this lot have not even turned up for work. I saw the warning signs on Saturday after only two minutes. In that time I witnessed Philippe Coutinho twice receive the ball and have time and space to pick his pass.
"Nobody was within 20 yards of the Brazilian. Not a tackle, not an attempt to close him down - nothing. This was supposed to be a Newcastle team determined to wipe away the memory of the 3-0 Sunderland defeat by putting in a spirited display.
"Instead, we got this."