Deila, the 38-year-old Norwegian, was unveiled as Celtic manager on Friday as McCann, who saved the club from financial ruin 20 years ago, was making the final adjustments to a 1000-word letter asking supporters to renew season tickets.
He told Herald Sport: "I?¯am keen to see Celtic progress so that is why I?¯asked the club for permission to write the letter. I?¯am looking forward to the new season and I?¯hope the fans get behind the new manager."
Celtic's recruitment of the former Stromsgodset manager was viewed as a surprise but McCann said: "I?¯am very pleased to see they have someone like that coming in."
McCann's tenure was marked by a combination of financial astuteness and ambition. It was his plan to build a 60,000-seat stadium and he explained that this was designed to increase the team's advantage at home. "It sits 60,000 for a reason and these seats should be filled," he added.
He praised the way Peter Lawwell, the current chief executive, and the board had run the club at a time when so many rivals are struggling.
"I?¯am fully supportive of the way they are operating; they are operating correctly in the very difficult environment that is Scottish football, I?¯commend them for it," said McCann, who added that he would like to see Celtic play in a "British" league alongside the best teams in England.
In his letter, he writes: "With your support and with patient, skilful management, Celtic have achieved great results in recent years, on and off the field. We have managed to perform well in Europe and compete with clubs who enjoy huge television revenues. And our club is financially strong and secure.
"But Celtic are playing under a great handicap. We are in a league that is limited by being in a country of only five million people. Although the standard of play has improved, most of our local opponents do not have the resources that come only by way of your support and of others like you. And the present absence of three old rivals [Rangers, Hearts and Hibernian, who will play next season in the SPFL Championship] means that some people wrongly see the winning of the championship as routine, not a challenge."
However, he said that the presence of fans was critical and urged all who could afford it to renew their tickets.