Celtic suffered a chastening Champions League night on Tuesday when they suffered a 6-0 defeat at the hands of Atletico Madrid at the Wanda Metropolitano.
The Scottish giants are now without a win in the Champions League group stage in ten games and are now sitting at the bottom of their current group.
McFadden pointed out that Celtic finished the game with young players who the Scottish giants are banking on to come good in the future and are treating them as projects.
He stressed that Celtic cannot rely on such youngsters if they want to do better in the Champions League and need players who can come straight in and make an impact.
McFadden said on BBC Radio Scotland: “You look at the players who came on and finished the game for Celtic, were these younger players who are supposedly projects?
“When you come to a place like this, against a team as good as Atletico, you need more than projects.
“You need players who can come on and have an impact in the game and Celtic didn’t have that.”
Celtic need to win their last two group games if they want to remain involved in Europe in the second half of the season.