As a captain, too, McStay has his critics. They complain that he never shakes a fist or screams at team-mates in the manner to which Parkhead patrons were accustomed when Roy Aitken or Billy McNeill wore the armband. Surrounded by sceptics, McStay must be tempted to ask: how did such a flawed individual amass 72 caps and an impressive array of medals?
Should he add to his haul in tomorrow's Tennents Scottish Cup final against Airdrieonians at Hampden Park, it is likely to tell us little or nothing about the skipper or his side. Airdrie are a First Division outfit, Celtic one of British football's great institutions.
Sometimes, though, McStay's detractors want to have their cake and eat it. In November, when Raith Rovers rose from Airdrie's level to beat Celtic on penalties in the Coca-Cola Cup final, his failure to convert the crucial spot-kick was seized upon as confirmation of his own and the team's shortcomings.
Mention that day at Ibrox and McStay's typically courteous response is prefaced by a sigh. "That's history now - it's become a bit of a bore," he said. "If anything, it makes me more determined to do well this time. But when I look back in years to come, I think the successes will outweigh the disappointments.''
Tommy Burns, Celtic's manager and a former midfield foil of McStay's, dropped him not long afterwards. "Paul was working hard, but the extra things that make him special were missing," he explained. "I told him that and he came back an even better player. He pushed himself harder than ever in training, which is difficult when you've been here as long as him.''
McStay, whose laid-back, Goweresque demeanour is frequently mistaken for faint-heartedness, "disagreed with the decision" but accepted it. "I was very upset at the time. I needed to say to myself: 'Right, what are you going to do about it?' I was fortunate that I had a lot of help from family and friends.''
Perhaps he was suffering a reaction to the fateful shoot-out? "Not at all," Burns said dismissively. "Paul was the best player on the park. All of a sudden he misses a penalty and ignorant people are screaming for his head.''
That final encapsulated the pressure under which McStay has always performed. Ever since his days as an adolescent prodigy, before he formalised his ties with the club in whose lore generations of his family were steeped, more has been expected of him than his contemporaries.
There seemed no doubt that he would fulfil his potential. He was named in the Fifa XI after the World Under-18 Cup in 1983. Full caps soon followed. Yet now, aged 30, he remains an enigma, filed under "perpetually promising".
McStay is accustomed to such sniping. "That's life in the big city," he said. "I've set high standards throughout my career and I'm up there to be knocked down. The hardest part of football is probably trying to handle situations like I've faced this year. I've come through it, and I think I'm playing well again.''
Burns, who described him as "the best player in Britain" after the semi- final victory over Hibernian, has been associated with Celtic long enough to put McStay's predicament in perspective. "He's been one of the few genuinely top-class players here in recent years, so he's been expected to pull everything together. He paid a price for that.''
Once restored to the team, McStay resumed his role as captain. Given that Burns calls him "a very reserved, quiet character, possibly even introverted", who goes about his business "without pushing himself", it could be argued that the additional responsibility places an unnecessary strain on the player.
"Paul leads by example rather than by running about bawling and shouting," Burns said. "He's not the perfect captain - some aspects of the job are foreign to his nature - but he has the total respect of the team.''
Jim Baxter put his finger on McStay's lack of punter-appeal by stating that he was not, in the Glasgow vernacular, "gallus". True, swagger does not come naturally to him. There again, by the time "Slim Jim" hit 30, he was better known for partying than passing. Unlike McStay, he never played in the World Cup or European Championship finals.
What McStay shares with the great Rangers schemer is a precious ability to bring colleagues into the game. One of Scotland's goals in Finland last September followed a build-up of 12 passes. McStay's third pass of the move, immediately before Tom Boyd crossed for Duncan Shearer to score, was threaded between two defenders with the outside of his right foot and had sufficient spin to make the ball sit up perfectly for Boyd.
"The best pass I've seen in years," enthused Craig Brown, the Scots' manager. This spring, McStay speared the defence-splitting ball which led to the penalty that knocked out Kilmarnock, and he created two goals in the semi-final. "It's vital he gets on the ball and influences things rather than staying on the periphery," Burns said. "When he controls the game, there's nobody better.''
This time three years ago, McStay threw his shirt to the crowd on the "Jungle" terrace, anticipating that he had played his last game for Celtic. There was talk of a transfer to Everton, or Udinese, or even across the city. (A letter to one paper quipped: "McStay for Rangers? Sounds a fair swap to me.'') Although he eventually re-signed, Burns concedes he might have benefitted from a move.
"If Paul had wanted to further his football education he should actually have gone in 1988. He'd just completed a double-winning year when he was head and shoulders above everyone else. I'm glad he stayed.''
What admirers cite as rare loyalty in an avaricious age, others regard as proof of his lack of get-up-and-go. Either way, his continued presence means he can still avoid the stigma of being one of the few Celtic captains never to raise a trophy. If McStay's quiet fire takes hold, the hoops may be too hot for Airdrie.Reuse content