The Magpies lost 6-1 at the Etihad despite a strong start.
The Dutchman was powerless to prevent a rampant Sergio Aguero from undoing all the good work Steve McClaren’s men achieved in the first-half and the Toon Army were foremost in his mind when dissecting what went wrong.
“Everybody knows that’s not good enough – that 10 minutes in the second half,” he told the Shields Gazette.
“I feel sorry for them. We had a lot of supporters here. They saw a very good first half, but then in the second half wasn’t good for them and they don’t deserve it.
“We are very disappointed, especially after the first half. It was really good, and then in 10 minutes we lost the game."
Newcastle started on fire and took the lead through an Aleksandar Mitrovic header after a beautifully worked move.
Their lead should have been stretched further but several gilt-edged chances went begging and Aguero’s header just before half-time was a signal of things to come.
The Argentine picked up where he left off and completed his hat-trick within five minutes of the restart before grabbing two more – with a Kevin De Bruyne strike sandwiched in between – to complete the rout.
Losing at the Etihad isn’t cause for dismay, but the manner of Newcastle’s first-half performance and their subsequent collapse in the second-half is an indication of the lack of confidence among the squad currently.
McClaren’s men never recovered from Aguero’s equaliser and seemed resigned to a heavy defeat as soon as it found the net.
The onus now falls on the former Derby County manager to lift his players for their upcoming run of so-called 'winnable' fixtures.