The Warriors slumped to a record eighth successive loss to Canterbury in the NRL's final round.
But fans of the Kiwi franchise have reason to expect big things next season given the acquisition of two of the biggest names in the NRL in Tuivasa-Sheck and Luke.
But McFadden believes the club needs to find out what went wrong over the final two months of the 2015 season first.
"We certainly can't ignore what happened the past couple of months and how we haven't handled the situation," McFadden said.
"When we sit back and reflect upon the season the young blokes and the experience they have gained that will be a positive.
"But we have had some circumstances that have been challenging, we haven't handled that and have to take responsibility for that.
"Clearly in the game in moments when you really need to hang in there, you need the players in a certain mindset and they were not in that and I have to take responsibility for that.
The loss of superstar playmaker Shaun Johnson to a season-ending ankle injury in round 20 was the deathknell to the Warriors' finals hopes.
But the week before that they had been belted by Sydney Roosters 24-0 in a match that was touted as a true test of their premiership hopes after they had moved into the top four.
"At the start of every new season, you are on a clean slate but we can't ignore the last few months," McFadden said.
"But we also can't ignore that after round 18 we got to fourth place. There are some positive things about that, these young guys are going to be far more prepared with the experience they have had and the quality we have coming in."
