With Parkinson's side struggling to get out of first gear all evening, City fell to defeat at the hands of the visiting Saddlers thanks to a second half double from Craig Westcarr.
The disappointing loss left the Bantams still looking firmly over their shoulder going into the last month or so of the League 1 campaign.
As most supporters have come to know and respect about the popular City chief, Parkinson was refreshingly honest and candid about his side's lacklustre showing and refused to make any excuses for the unacceptable display.
Parkinson said: "It was a poor performance from us tonight (Tuesday).
"I felt the discipline of the team was relatively good in the first half but we never looked like we were going to create anything throughout the entire game.
"We didn't get enough crosses in the box and we didn't threaten the opposition goal.
"We didn't work the 'keeper at all.
"In all the time I've been here, I cannot remember a performance where we have offered so little in the final third.
"We have to look for reasons for that. I am particularly disappointed by our play after we conceded the first goal.
"There was a lack of a response from us after their first goal.
"Whether we have won, drawn or lost in the past, our supporters have usually seen us play with a fighting spirit, but they didn't tonight.
"The fans were right to boo us off the pitch.
"We looked like we lacked energy. We really need to push ourselves harder to get back into games than we did tonight.
"It was a soft goal to give away and that can sometimes knock you back a bit, but we've come back many times after conceding in the past, especially when attacking to that (Kop) end.
"As I say, the first goal was a sloppy one to give away, but the main concern for me was the lack of drive to try and come back after we had conceded."
Skipper Gary Jones returned to the side after recent illness but was then replaced nine minutes from the end of normal time.
Parkinson added: "Gary was not been feeling great recently and the illness did knock the stuffing out of him. He's feeling better now though but I just felt we needed some fresher legs in the final ten minutes or so of the match.
"As usual, Gary had ran himself into the ground."
City's two other changes from the weekend saw Matthew Bates play in central midfield and Andy Gray start up front following James Hanson's on-going back problem.
Parkinson said: "(Matthew) Batesy has played central midfield at the highest level and we certainly won't be putting any blame on him for the defeat just because he wasn't playing in defence tonight.
"Andy Gray worked his socks off, which wasn't easy for him considering it was only his second start of the season.
"He needs crosses into the box, however, and we didn't give him anywhere near enough.
"He can score from crosses - he's a good finisher - but we didn't get enough quality in for him."