The 3-1 defeat at Craven Cottage pushed the west Londoners closer towards the precipice, with five points now separating them from safety with only six matches remaining.
Bent was again reduced to a watching brief for for the match, with Magath instead preferring teenagers Cauley Woodrow, Moussa Dembele and Patrick Roberts.
The German manager revealed afterwards that the former England international missed out because he had taken a knock in training on Thursday, insisting "it was better to put the players in who are really fit" - comments that bemused Bent.
"I trained on Saturday," he told reporters. "I'd taken a knock and limped off quite early in training on Thursday but I've trained since and felt fine on Sunday. It is just disappointing.
"I was fine to play. I am disappointed not to feature, especially in games like the Everton match where you feel that you can definitely affect the game, when your team needs a goal.
"Over the years I have managed to produce quite a few of those.
"When the team got back to 1-1 you are thinking: 'You can make a difference here.' But once again it was not to be. That part is disappointing.
"When you are a substitute in any game, it is disappointing, but especially today. All I can do is stay positive and keep working."
Bent has not featured for Fulham since coming off the bench in the 3-1 defeat at Cardiff on March 8 and has made just 10 starts for them this term.
It is an understandably frustrating time for the on-loan former England international, who is ineligible to face parent club Aston Villa this weekend but still hoping to be able to make an impact.
"It is getting difficult to see how I can contribute now as I can't play next week against Villa, because of the loan," Bent said.
"I am here, up for selection and more than willing to play. That is what I do, that is what I love to do. That will never change.
"At this stage of the season you need goals. You need firepower. If I am called on, I am ready to go. If I start up front, I am ready to go."