The Clarets lost 2-0 as Georginio Rutter and Yasin Ayari struck for the hosts.
Afterwards, Parker didn't mince words, stating: “We were poor - really poor. We didn’t deserve anything from the game.
“We lacked belief. We were miles off the standards we expect and that’s the first time I’ve said that of this team this season.
“I’m the first to praise my side but we made it too easy for them today. We didn’t do ourselves any favours at all today. We were never in the game.”
Parker continued: “Conceding early in the second half was disappointing. It was the worst possible time to concede a second.
“But overall we weren’t good enough.
“We had that one chance just before half-time but that would be clutching at things. We had very few positive moments.”
He added: “We need to re-boot and show something very different in a few day's time against Manchester United.
“Today’s display has amplified the need for a performance at Turf Moor in midweek.”