The Bhoys were beaten for the third time in the Scottish Premiership on Saturday when they suffered a shock home defeat against St Mirren.
Celtic are still 23 points behind runaway league leaders Rangers, but have only two games in hand, and face an almost impossible task to retain the title.
Bhoys boss Neil Lennon has taken aim at his players and accused them of letting him down, but former Hibernian and Dundee boss Duffy is sure that they are putting effort into games.
The 61-year-old feels that instead Celtic’s players are suffering from a huge lack of confidence, which has been noticed by opposing sides.
“It’s not a case of them not trying. You can see players sprinting back, you can see players sprinting forward”, Duffy said after Celtic’s loss on Clyde 1’s Superscoreboard.
“But confidence in football at any level, you can lose confidence and belief and that is what is happening with Celtic just now.
“They are making basic errors and they’ve lost that fear factor.
“For the last nine years Celtic have pretty much had a real dominance of Scottish football because teams were fearful.
“You went to Celtic Park and thought if you lose one or two nothing you’re actually quite happy.
“Now teams are having a go because the fear factor has been removed.”
With the clock ticking down in the transfer window it remains to be seen if the Bhoys opt to strengthen their squad before the deadline on Monday.
