The prop fell out of favour in the capital and was told in February that his contract would not be renewed at the end of the season.
It led to an anxious time for the 25-year-old who had to come to terms with trying to find a new club for the first time in his pro career.
Capped by Scotland in the Six Nations at the age of 21, McCallum’s progress stalled at Edinburgh last season as now departed coach Richard Cockerill looked to other options at tighthead.
Danny Wilson rode to the rescue, offering the Kirkcaldy-born forward a chance to impress at Scotstoun. McCallum, who worked with the Glasgow boss in the Scotland set-up, feels he has “landed on his feet” and is relishing the opportunity to work with a new management team which also includes Al Dickinson, the highly respected former prop who has joined the Warriors as scrum coach, and Nigel Carolan, the club’s new attack coach.
“I need to focus on my game and not worry about anyone else apart from what the coaches want me to do,” said McCallum. “And Danny has been quite clear in what he wants me to do and that helps me massively. He knows what my strengths are, what I need to work on and what he wants me to bring to the squad. It’s about having that love to learn again. And that’s been reinvigorated by joining Glasgow.
“I’ve improved already. Sometimes you just need a fresh voice so Nigel’s a fresh voice to everyone here. And Danny, Kenny Murray, Pete Murchie and a full-time scrum coach in Dicko. I played with him so that’s a pinch myself moment now that I’m coached by him.”
McCallum has until the new year to impress and win a longer-term contract. He knows competition with be tough with internationals Zander Fagerson, Simon Berghan and Enrique Pieretto all vying for the No 3 jersey.
“We’ll see what the boys upstairs think after a few games,” said McCallum who was involved in both of Glasgow’s pre-season matches and has his sights set on the United Rugby Championship opener against Ulster in Belfast on Friday. “I could be here for the year, I could be elsewhere. We’ll wait and see. But my focus at the moment is on these six months and however many opportunities I get. We’ve had two good pre-season games against Newcastle and Worcester, really good opposition. Newcastle was rusty, certainly on my part. I hadn’t played in a little while.
“I think the last game I played was at loosehead and that was in April or May. So it was good to blow the cobwebs away and get two games against top quality Prem opposition, especially coming into the Ulster game. Talk about getting chucked into the deep end at the start of the season! Ulster away at the Kingspan’s going to be brilliant and I’m really looking forward to it.”
While he was used sparingly last term, McCallum played 63 times for Edinburgh across five seasons and won three Scotland caps in 2018. Tighthead was a position of strength at the club and he admits it was a dogfight at times as he vied with the likes of WP Nel, Berghan, Lee-Roy Atalifo and Pietro Ceccarelli for a starting berth under Cockerill.
“They were all international players and I was still reasonably young,” he recalled. “It was the first time I’d had to fight and there were maybe sometimes I was frustrated and I maybe didn’t know how to handle it.
“I thought I was doing everything I could but who knows - sometimes it’s my word against the coach’s and at the end of the day he picks the team and if I’m not picked, I’m not picked and sometimes I struggled to deal with that. It is what it is. I had a couple of friends who had been in that situation who are a bit older than me and I spoke to them and asked them ‘what’s the crack here - how do you deal with this?’
“And it does get a bit twitchy at times, particularly in the Covid era when clubs are a bit more strapped and are maybe trimming back squad sizes. It’s a case of who’s got space or who needs someone like me? And lucky enough it was Glasgow who are in the Champions Cup this year and have made some really exciting signings and have two Lions boys coming back.”
Fagerson - one of the Lions boys, along with scrum-half Ali Price - is well known to McCallum as they used to play together in the Strathallan school team, with the former switching to the other side of the scrum to make way for the latter. McCallum doesn’t expect his old buddy to be as obliging now that they are team-mates at Glasgow.
“I’m delighted to see him coming back,” said the new boy. “I don’t see him moving over to loosehead to accommodate me any more! If Danny wants me to cover loosehead I’ll move across. I’ll go wherever I’m needed as the main thing is to be back playing rugby and loving it again.
“You can get into a rut where you’re only playing once in a while and put so much pressure on yourself that you almost forget what you should be doing as you’re so focused on trying to get picked for the next game. I just need to sack that and just focus on the game I’m playing in. I’d hope time is on my side at 25. I certainly don’t think I’ve cracked it. I might not have cracked it at 35!”