For a guy who is used to playing games in such prodigious numbers that his former Celtic team-mate Callum McGregor once called him a freak, last season and the early weeks of this one must have been a difficult experience for Kieran Tierney.

Arsenal have evolved as a team — from soft touches to second-best — but the evolution clearly does not hold a place for the Scot anymore. To start just six Premier League games last season was a glimpse into a world he had no desire to be part of. To not feature at all in the opening league games of this season was just too much.

Some footballers can tolerate being out in the wilderness at their club as long as the money keeps rolling in. Tierney is not one of those characters. He’s already rich and, while the money is great, it’s not everything to him. Mostly what he wants to do now is play. He would become unhappy at not playing.

So he’s away to Real Sociedad where his debut could well be against Real Madrid at the Bernabeu the week after the international break. Other Premier League clubs expressed an interest in him, but of the places he could have gone to he made it known his number one choice was Sociedad.

A new league, a new challenge. Given that Sociedad are paying Arsenal a loan fee as well as 100 per cent of his salary — a one-season commitment of £7m — the expectation is that he will start, which is the entire point of the move. After that, who knows? Football is odd. Not that long ago he looked like he was going to be a mainstay of the Mikel Arteta rebuild.

Sociedad do not spend money with abandon. They are not Real Madrid or Barcelona. In the summer of 2022, they made £63m on the sale of Alexander Isak to Newcastle and used it wisely, strengthening a squad and finishing fourth to make the Champions League for the first time in 10 years.

Europe’s pre-eminent club competition has to have been a big part in Tierney’s decision to go to Spain. It’s been almost six years since he played in the Champions League as a Celtic man and, though the competition has a mighty allure for him, it’s also populated by ghosts.

Tierney played in Celtic’s 7-0 loss to Barcelona and in their 5-0 and 7-1 drubbings by Paris St-Germain. He’s played nine games in the Champions League and has won only one of them — against Anderlecht. Having another crack at it will excite him.

Things have changed dramatically for Tierney since he made his Premier League debut against Crystal Palace in October 2019. Unlike now, Arsenal then bobbed around in the no-man’s land of eighth place in the Premier League.

His partners in defence on his debut were Sokratis Papastathopoulos, Calum Chambers and David Luiz. It’s a measure of the rebuilding work Arteta has done that nine of the starting line-up that day have all moved on. Tierney is the 10th and, though he might be back - he still has three years left on his deal - you would not bank on it.

The other is Nicolas Pepe, who is still an Arsenal player but probably not for much longer if they can move him out, as they did last season, on loan to Nice.

In his early days at Arsenal, Tierney became something of a standard bearer. He had a bond with the fans.

He had a humility and an honesty, qualities that the supporters appreciated in dark times on the field. He was regularly mentioned as one of a small group of players who could hold their head up week on week. They relied on his energy and his work ethic.

Tierney stepped into another world when he traded Glasgow for London. He was photographed turning up for work one day with his boots in a 10p shopping bag. The place he moved to lauded him for being an outlier, for refusing to go down the conventional route of designer stuff, like most of his contemporaries.

The place where he moved from came at it from a direction that he would have identified with most.

There was good-natured slagging for choosing a bag from one of the mid-range supermarkets rather than one of the more budget ones. Tierney, it was said in jest, was getting above himself.

With his attitude rooted in hard graft, there was chat that he was an Arsenal captain in the making, sparked by Martin Keown, a legend of the club.

Keown, and others, liked Tierney’s lack of airs and graces. In the cold of winter he would turn up in a T-shirt and shorts when team-mates would be cowering in hoodies and snoods. He looked like the type of fella that Arsenal needed - a guy with a resilient mentality who could bring some leadership.

As Arteta reshaped his team and brought in influential players, Tierney’s importance reduced. They needed him when they were struggling but the manager had others to do the heavy lifting now. In came Martin Odegaard and Ben White, Gabriel Jesus and Oleksandr Zinchenko, Gabriel Magalhaes and Thomas Partey.

Tierney was still deemed to be among the shortlist of contenders to be the new captain for 2022-23. In the dying minutes of a game against Watford in March 2022, he assumed the captaincy when Alexandre Lacazette went off.

Arteta had Odegaard, Granit Xhaka and Partey on the field but the armband went to Tierney and it was hinted by the manager that he might keep it. Instead it went to Odegaard, who led the team well in their tilt for the title, a challenge that involved Tierney now filling the role of back-up left-back. You might argue that Arteta’s revolution outgrew him.

The move to Spain is not only a relief and a huge opportunity for the player, it’s also good news for Scotland. Tierney’s performances for his country last season were exceptional, all the more so given how little football he was actually playing for his club in the lead-in to those seismic internationals that have helped put Scotland in the box-seat for Euro 2024 qualification.

In almost six months before the March double-header against Cyprus (a routine 3-0 win) and Spain (a defining 2-0 win), Tierney’s average league game time for Arsenal was 13 minutes. He tore it up against Spain.

He did that while out of the team at Arsenal and uncertain about his future — and it was deeply impressive. With stability and regular starts at Sociedad the next phase of Tierney’s career is about to begin. At 26, the feeling is that his story is only really getting going.