The experienced centre-back returned from a calf problem as the Clarets suffered a 1-0 defeat to Hull at Turf Moor on Monday night - the fourth time they have drawn a blank in the past six matches.
It is a slump far removed from their free-scoring early season form, when Charlie Austin briefly rubbed shoulders with Lionel Messi and Cristiano Ronaldo among Europe's top marksmen.
Sean Dyche has instilled some much-needed defensive solidity since replacing Bournemouth-bound Eddie Howe as manager, but Duff would like to see the spark rediscovered ahead of Sunday's derby clash at Blackburn
"We scored a lot at the start of the season because everything Charlie hit went in," he said.
"Charlie had a vein of form where he didn't even have to look at the goal - it would come off his heel and go into the net.
"But we were conceding too many goals and that's the fine balance. You get teams who score a lot and concede a lot or teams that nick games 1-0.
"It is trying to get that balance. From the defenders' point of view we don't look like conceding many goals.
"The goals have dried up a little bit and maybe more of the chances have dried up, which is the more worrying little thing, but, again, a lot of it's (down to) confidence.
"We've got a lot of good players and we just need to get them on the ball a little bit more."