The Norwegian manager took over the Hoops three years ago to the surprise of many, but apparently showing enough with Stromsgodset in his homeland to suggest he could make a success of it.
Although he resigned after pressure around his team’s performances and results, Deila won three trophies during his time as manager, including back-to-back league titles.
There’s no doubt he made some big changes to the club after Neil Lennon’s spell in charge – and the majority of fans should look back on the Norwegian’s tenure positively.
But how does Deila look back on it?
He’s now back in Norway managing Valerenga and talked about his time at Celtic while appearing on podcast Fotballklubben recently.
It’s been brilliantly transcribed by 90minutecynic.com and his thoughts on the condition of some Celtic players when he joined the club is an interesting read.
Deila said: “As a manager in Britain, you’re above everybody else. You’d never have a prank made on you or something like that, it’s total respect. They don’t even call you by your name, it’s just ‘’gaffer’’. The hierarchy is very fixed and strong in Britain. It’s a big thing being captain as well, you’re in charge of the group. Your captain is your right hand on the pitch and for me Scott Brown was great, we had a very good relationship, which was important. He was an essential player for me and he still is for the club.
“In a way, the culture within the squad was similar to Norway 15 years ago, both in a good and bad way. It’s a tougher atmosphere, there is more yelling and harsh criticism between players. This is something we need more of in Norway; a winning mentality, big personalities driving each other on. You need to have something special about you if you are to succeed at the top level.
“However, they were not as conscious around nutrition and the concept of being a “24-hour athlete” as we are in Norway. Quite frankly, it was shocking, but it had a lot to do with the wider society in Britain and the diet norms. It’s fried food, there is sugar in everything, alcohol, basically all the things that are the worst imaginable nutrition wise. We had to change everything about it at the club. I said to the nutrition expert at the club at the time that players can’t eat cornflakes for breakfast, and the answer I got was that they don’t like anything else! For me it would be better not to eat breakfast than having cornflakes, which they didn’t agree with’
“The player’s fat percentage was being measured at Celtic but I didn’t trust the readings; on some of the players I couldn’t even see their abdominal muscles. I brought in the nutrition expert I had worked with at Strømsgodset and it turned out that I was right; the measurements were wrong and too lenient, the fat percentage was actually higher.
“In my first six months at Celtic the squad lost a combined weight of 60 kilos (9 ½ stones). John Collins had a very European mind-set when it came to fitness, having played at Monaco. He was fitter – at almost 50 – then some of the players in the squad when I arrived.
“It was difficult at the start but we achieved some good results and got the players on board. After all, everybody wants to have a better beach body! Virgil van Dijk weighed 104kg (16st 4lb) when I arrived and when he left for Southampton he was 95kg (15st) and looked like a proper athlete. He was the best football player I’ve ever coached but 9kg (1st 4lb) will have a big impact on your ability to quickly move around the pitch.”
Deila then went on to talk about the drinking culture at Celtic – highlighting how it was actually important for improving the mood of the team.
He added: “The drinking culture was different. It is a lot more of a working-class culture within football in Britain – which there is absolutely nothing wrong with – and everyone was professional before games as you just can’t get away with drinking regularly if you have 60-70 games a season and with the intense media scrutiny there is on players.
“But when they are given the opportunity to drink, they do it properly, which is fair. Especially because they do it together, something we also used to do in Norway. You don’t go out separately, you go out as a team. You must be able to trust each other out on the field, in good times and bad times. You must experience things together, celebrate together and it should be painful when you lose with people telling some harsh truths. To achieve that kind of relationship you have to spend more time together than just at training.”