The Celtic boss was discussing the beleaguered striker.
Scepovic has found it hard to get much game time since signing for the Hoops, despite scoring several goals for the club this season.
And Deila admits it's been 'different' for the Serb, who he believes has struggled with the tempo of Scottish football despite having 'a lot of skills.'
The Norwegian also suggested the competition from Leigh Griffiths and John Guidetti has proven too much for the 25-year-old.
Deila explained to reporters: "He’s still a project. We had to work on that. It’s been different for him. The style of playing maybe, the tempo in the games is not what he was used to.
"But he has a lot of skills that we can use and need and he’s been working hard. He really tries to do everything he can so it’s tough. The competition has been harder. Leigh [Griffiths] has done well, before Christmas it was John [Guidetti] scoring a lot of goals.”
Meanwhile, Deila didn't rule out the possibility of the Bhoys parting company with Scepovic at the end of the season.
While the 39-year-old was keen to defend the striker, he did emphasise the need to see improvement in his players, with a natural repercussion of a lack thereof being a potential sale.
Asked if the Serb could be on the move this summer, the Celtic boss gave a coy response: “[With] every player, we have to see improvement all the time. It’s not only Stefan. It’s about every player.”
Celtic travel to Aberdeen later today. Ahead of the clash, Griffiths has been named SPFL Player of the Month for April, demonstrating just how hard it is for Scepovic to break back into the side.