Graham Kavanagh said Carlisle could not cope with hat-trick hero Jay Emmanuel-Thomas, who inspired Bristol City to a 4-2 win.
City's triumph, their first three-point haul since March, came by way of a second-half hat-trick by Emmanuel-Thomas and Scott Wagstaff's thunderbolt, which secured City their first away victory since December.
Carlisle led at half-time through a Sean O'Hanlon header, but Thomas scored twice inside a minute after the break and Wagstaff added a third.
Although Liam Noble pulled one back for the home side, Thomas was again on target for City to make sure of the victory in the closing minutes.
It was a return to Carlisle's early-season habit of conceding soft goals, although the Robins were value for their first win in 22 league games.
"Thomas was a handful all game," Kavanagh said.
"We knew he would be a threat and talked about it before the game. We handled him alright in the first half, but could not deal with him in the second.
"We had a bad day at the office in terms of the result, but the lads put a good shift in.
"The work ethic and honesty was there, but we lacked a bit of intelligence at times. We were reactive rather than proactive.
"You are never happy to lose, but the biggest positive was the way the players reacted. It is a huge learning curve for some of them."