The hosts took an early lead through Niall McGinn but Hibs hit back through James Scott’s first goal for the club. Josh Mulligan restored Dundee’s lead and Charlie Adam made the points safe with a wonderful strike from distance late on.
Speaking afterwards, the caretaker manager lamented his side’s decision-making but insisted his players weren’t putting the brakes on as the season winds down.
“We lacked quality at times, our decision-making was poor. Taking responsibility is something we need to get better at,” he said.
“It was a very disappointing evening.
“It would be easy to use the managerial situation as an excuse, or to say that the season is finishing now or whatever. That’s never the case.
“It’s professional football, you get paid to play and to perform to the best of your ability every time you pull on the jersey. You’re in a privileged position.
"From an attitude point of view it should always be spot-on.”
The 34-year-old appeared to suggest that his side had been poor defensively as he looked back on a disappointing 90 minutes.
“I don’t think it’s a case of not trying. I think the players try, I think they have been trying all season.
"It comes down to individuals at times, it comes down to doing your job, whether that’s stopping crosses, defending the box, just being better than your opponent and now allowing them to get the better of you.
“Charlie’s goal was a very good strike but so avoidable from our point of view.”
Gray refused to use the club’s extensive injury-list as a factor, adding: “I think we’re a little thin at the moment and limited in what we can do but that’s not an excuse, the situation hasn’t changed in the last three or four games and isn’t going to change before Sunday.
"We’ve got what we’ve got, we don’t have time to feel sorry for ourselves. The players need to dust themselves down and myself and Eddie [May] need to get them as ready as we possibly can for another tough game at the weekend.”