The Shakers had gone into the game on the back of a morale-boosting win at Swindon last Tuesday, but two goals from Jamie Proctor secured Crawley boss Richie Barker a win on his first return to Gigg Lane since quitting as Bury boss in August.
After Saturday's League One encounter, Blackwell said: "I can only apologise to our supporters for that - we were awful - absolute rubbish.
"The boys were high as kites after the win on Tuesday so I just don't know where that performance came from to be honest.
"We never really got going and conceded two poor goals.
"All we can do is put that in the box, send it on its way and move on to the next game."
Proctor opened his account in the 16th minute when he controlled a pass from ex-Bury midfielder Mike Jones on his chest before hitting a left-footed half-volley past Bury goalkeeper Trevor Carson from 15 yards.
Proctor scored again two minutes into the second half when he planted a firm header from Jones' cross past a helpless Carson and after that the visitors were content to soak up pressure and try and hit Bury on the break.