On United's defensive woes, Shearer said: "In [Aaron Wan-Bissaka and Diogo Dalot's] defence, they got no help whatsoever from [Alejandro] Garnacho and [Marcus] Rashford.
"Rashford didn't look at it at all - didn't look interested. It happened so many times. Newcastle created so many chances and they should have had many goals.
"For me, there are too many bad eggs in that Man United team. Too many bad attitudes.
"It's alright when things are going well for you, you can get your feet on the ball, play and pick your head up when things are nice and rosy.
"But, when it's not going for you, when you're a bit tired and you've got to roll your sleeves up, there's not enough characters in that team."