Celtic’s want-away players should consider recent history. It’s not been kind to them.

It’s common currency amongst our supporters, I think, that we’re going to lose a top player during this summer of fun. We don’t know who the player is going to be yet, although it looks most likely that it’s going to be our German winger, Nicholas Kühn. The thing is, he’s going to have to be very careful. A lot of these guys have made mistakes. When I say a lot of these guys, I mean very recently.

Celtic has had real top-class success stories who have left this club and gone on and thrived. But there aren’t a lot of them. Not as many as you might think until you look at the record. We know about Virgil van Dijk. Big Virgil went to Liverpool and never looked back. He became an elite-level defender. We all know that Jeremie Frimpong went to Germany and excelled. He’s now at Liverpool too, having netted us a very nice little chunk of change on the move—just as van Dijk did when he went there.

Other guys have certainly made a lot of money since leaving the club. We know that Moussa Dembélé is over playing in Saudi Arabia. The cash must be good there, but that’s about all. The football certainly isn’t. Although he’s doing well at that club, is that really where the boy thought he was going to be just six or seven years ago when he left Parkhead? At that time, he had scored Champions League goals. He was a scalper extraordinaire of our Glasgow rivals. A lot of people thought that if he made the right move, he would end up a French international. He’s nowhere near it.

The same could be said for Odsonne Edouard. He too left in the last few years, and he too was expected to go on and quite possibly pull on the blue jersey of the national team. His move has, if anything, been even more calamitous than that of Moussa. He has struggled to justify his name, his reputation, and his pedigree. He’s got to get the next stage of his career right. He’s got to find more in his locker than he has so far. He has all the talent in the world. So what the hell has gone wrong?

If you want to look at the cautionary tale to end all cautionary tales, you would look at Jota. Like Moussa, he went to Saudi—but he went there much earlier than most did. Moussa played in France for a while at a top club, Lyon, although it wasn’t a greatly successful spell. Jota went straight from Benfica to Celtic to Saudi without missing a beat, and it was the worst thing he ever did in terms of football. That boy lost a year of his career. Now, out through injury, he might lose another year. That’s a terrible waste. I still think we’re going to get one hell of a player when he comes back to fitness, but aside from the money, I think he probably has a lot of regrets.

Kyogo definitely has a lot of regrets. He probably has nothing but regrets. He could have stayed at Celtic for six more months anyway—completed the season, played in the Champions League against Bayern Munich, and made a contribution to the cause towards trying to win the treble. We may even have done it had he been in our ranks. But rather than feel sorry for ourselves, I actually look at him and I think that if ever a player was badly served by his so-called advisers, it is him. He listened to too many voices whispering in his ear. That’s what I think. And that’s what I’ve thought since he left.

Matt O’Riley went to the wrong club—Brighton. Again, part of that was just bad luck. He got injured almost immediately and missed several months. He scored against Manchester City—a match-winning goal—and at that point you think his star is only going to rise and rise and rise. But it doesn’t. He falls out of the side. He drifts out of favour. All of a sudden, he’s not in the team at all except for sporadic appearances from the bench.

And yet, deliverance is at hand. The boys from Naples have been watching. They see something. They already have a couple of British players in the ranks—the two Scots, Billy Gilmour and, most importantly, Scott McTominay, who has probably progressed more in the space of 12 months than any player I’ve ever watched. Genuinely, he looks a class apart in that Napoli team. And if Matty follows him there, O’Riley will be a huge success at that club.

But “if” does a lot of heavy lifting in that sentence. Napoli still have to be genuinely interested. They have to make a bid Brighton finds acceptable. O’Riley has to go there and agree terms. And then he has to get into an exceptionally strong midfield which is preparing for Champions League football next season as defending Italian champions. So it’s not going to be easy. But O’Riley does have the talent to crack it, and that’s why I was so surprised that he didn’t do better whilst he was in England.

But look how many players that is—who, in a very short time frame, left this club expecting to go on to bigger and better things and have seen their moves unravel. Some disastrously. It may well be that there are happy endings for a lot of those guys. Edouard might get the move he needs this time to the right kind of team and might set the world on fire. Jota is home, where he’s supposed to be, and he will make a big contribution to our club next season—even if he misses the first half. Kyogo will probably find a good club that appreciates him and plays him in the right position, and he’ll score goals and rebuild his career somewhere good. Matt might get the big move and end up playing top-class football for a top-class side and realise his enormous potential.

But like I said, that word “if” is doing a lot of heavy lifting again. None of that is certain. And some of it, in fact, is very uncertain.

But players are going to do what they’re going to do. If Nicholas Kühn thinks that he’s going to make more money and play at a higher level going somewhere else, then nothing’s going to talk him out of that. The only thing that might eventually make him see the light is if he does go somewhere and finds himself benched. Or if he suddenly can’t hit form. Or—and this is a big one, and this one catches a lot of them—they go to a team that doesn’t play their style of football, a style that suits their game.

You’re not going to convince people to stay unless your wages are competitive—when they can go and earn five, six, seven, eight times their salary. For some of these people, that is the driving force. For others, they want to go and play at that higher level. They want to go and experience football at the very top, to play against better players, to test themselves.

The thing is, though, some of them aren’t going to pass that test. And for many of them, that’s a harder lesson than they ever expected—and it’s a tough one to take.

It was only last night when I was sitting thinking about Kühn and where he might end up that I realised how many of these guys who have left in recent years have, if not regretted it, then certainly not found the pot of gold at the end of the rainbow they were expecting. The money? Sure. I’m certain none of them will ever have to worry about getting a job writing for the Daily Record—they played at the wrong club for that.

But satisfaction? The pleasure of being out on the pitch and playing. The pleasure of seeing their name in the headlines for all the right reasons. They never got anything like that, and some of them never will again.

If Nicholas Kühn wants to go and chase the money, there’s nothing we can do to keep him. If he thinks he’s outgrown Scottish football, then he may be right. But he’s going to have to prove that he’s grown up enough to handle it at a higher level. And that might not be as easy as he seems to think.

So he needs to be careful. Anyone who leaves Celtic needs to be careful. So many of them have found that they didn’t really know or appreciate what they had—until it was gone.