Terry Butcher spoke of a player who was making progress and had yet to show his best, but all fans saw was a diminutive striker who had only managed to score three goals in his first season.
It has not taken long for McKay to vindicate the decision of his manager; the Northern Irishman having now scored 13 times this season – seven of those coming in his last five matches – while exhibiting all the traits of a player at the very top of his game.
Confidence is often said to be a commodity every forward thrives on and the ease of the 24-year-old's finishing against Ross County in a William Hill Scottish Cup fourth round replay on Tuesday night were testament to that. Indeed, the former Northampton Town striker is now challenging Hibernian's Leigh Griffiths to be considered the most proficient striker in the Clydesdale Bank Premier League.
Butcher's decision to award that unexpected contract extension has also removed one of several minor headaches for the Inverness manager in the lead up to January. Whereas other in-form players at the club such as Aaron Doran and Andrew Shinnie are free to talk to suitor clubs next month, McKay is tied up tight – a rare situation for a club well-used to losing its brightest lights during the transfer windows.
For Gary Warren, who won the penalty from which McKay scored his first against County this week, the striker is among the hottest properties in the Premier League. "Billy has been outstanding for us and he got us through to the Scottish Cup fifth round with an exceptional goal," said the Inverness defender.
"He is scoring goals for fun and would be a hot property for any club given the way he is performing right now. There could obviously be interest in him but he is under contract and I hope he stays here."
The interest in McKay has already extended to the international arena, with the Northern Irishman invited to join with his country's senior squad for the first time last month. Warren is confident that goals will prove to be the currency needed for his young team-mate to acquire his first senior cap.
"Billy has been on fire for the last 10 to 15 games really," Warren said. "He should be in the running for a Northern Ireland cap now due to the way he is playing. In this form, he is the best striker in the league and with the goals he has scored he should definitely be in the running for international recognition."
McKay's goals against County have also kept Inverness in the running in the Scottish Cup. Butcher's side are the form horses in the country at present and are the top scorers in the top flight having notched 34 goals in the campaign to date. Warren says there is more to come from the team.
"We are in the semi-finals of the League Cup, second in the league and there is no reason why we cannot go on another run in this cup," he said. "I played in the FA Trophy final last year for Newport County when we lost 2-0 to York City and it was a big highlight of my career to play at Wembley. To get to a cup final this season would be even better and to make it a double by playing at Hampden would be fantastic. I've never even been there, so to play there would be great.
"A lot of people questioned us at the start of the season but we didn't lose many games. Players were blending in but you are seeing the best of us now. I don't see why we can't keep getting better."