On a day when it wasn't exactly thrill-a-minute as Ally McCoist's side booked their place in the fifth round of the William Hill Scottish Cup, the 17-year-old winger managed to provide a bright spark at Ibrox during a comprehensive if unspectacular 3-0 victory over Elgin City.
While many presumed the arrival of seasoned SPL stars such as Dean Shiels, Ian Black and Fran Sandaza would inject that added bit of quality into Rangers' performances this season, it has been the emergence of McKay that has made one of the biggest marks with the Light Blue legions.
If anything, Shiels and Black have been a disappointment considering they were both the best players at their respective clubs, Kilmarnock and Hearts, prior to dropping down the divisions to bolster Ally McCoist's bid to progress back up to the SPL.
There have been moments in matches when Shiels has conjured up something special from nothing. It was the case once again yesterday when he netted the opening goal, but his influence on his team's play could definitely be greater.
The same can't be said of Black who has been average at best during the opening few months of the campaign.
McKay, however, has been a breath of fresh air when he has been involved. Certainly, that was the case yesterday as he turned on the style to help Rangers defeat their fellow Irn-Bru Third Division rivals. If anything, he makes a match far more exciting when he is in possession of the ball.
He's the height of nonsense and looks more like a mascot than a first-team player, but he has pace to burn and, at this level anyway, can glide past defenders as though they aren't there. Add to that an eye for a defence-splitting pass and you have a player well worth watching.
It is, of course, important to remember he still has a long way to go before he can consider himself as an automatic starter at Rangers and, moving forward, prove himself good enough to operate at the top level.
McCoist knows there will be times when he'll have to take him out of the team to avoid burning him out but the Ibrox manager also knows he has an extremely talented youngster on his hands and was delighted with the way he performed in yesterday's victory over Elgin.
"I was delighted with the wee man," smiled McCoist.
"I thought his first-half performance especially lit up the stadium at times and the supporters respond to him when he is on the ball.
"They enjoy watching him run at defenders and trying to make things happen.
"He is really quick and direct and some of his general play belied his years.
"Barrie is only 17-years-old but he looks so composed out there and comfortable in that sort of environment.
"He has worked hard to get to where he is and is making the most of the opportunity."
Although striker Kevin Kyle was not anywhere near as good as little McKay, McCoist was equally pleased with his contribution.
The former Hearts target man kept his place in the team and helped create Shiels' opener. He also doubled his side's advantage after heading home a McKay corner in the second half.
The 31-year-old still looks as though he has some way to go in becoming more mobile on the pitch to help contribute to a greater extent.
However, it hasn't stopped the Stranraer native from earning the brace of his boss.
McCoist added: "Kevin got his first league goal last time out so it was important he continued with his form and his progress and I thought he did that. He also had a big hand in our opening goal."
While the priority remains winning the Third Division championship, McCoist does harbour ambitions of enjoying an extended run in the Scottish Cup.
And the Ibrox gaffer feels they might now be in a better position to do so than they were in the Scottish Communities League Cup after crashing out to Inverness .
He said: "The league is our main target but I've always said if we can do well in the cup competitions then that would be great.
"Yesterday was a difficult game because Elgin City are a team who score goals and we managed to keep a clean sheet and score three good goals ourselves.
"We have a young, inexperienced team. Five months ago they didn't know each other let alone play with each other.
"We are improving. It was also nice to see young Kal Naismith come off the bench and score our third goal.
"We'll take our chances in the cup, but we now have a run of league matches this month and we need to focus on them."