The clue is to be found in the fact that three of the four goals were delivered by their principal strikers, Jan Vennegoor of Hesselink and Scott McDonald, and the other by the central defender, Stephen McManus.

During the immediately preceding run of one win from five matches – a sequence in which they dropped seven points to Dundee United, Rangers and Motherwell and were eliminated from the Scottish Cup by Aberdeen without scoring a single goal – it would have become obvious to anyone paying even cursory attention that, in the event of their strikers suffering a loss of productivity, there was no-one who could be relied upon to compensate.

Championship-winning teams are almost invariably served by midfield players who make a significant contribution to the goals-for column. Of Celtic's 73 league goals this season – the same number as the leaders, Rangers, despite the recent failures – only 18 have come from the four most-picked midfield players, Scott Brown, Massimo Donati, Aiden McGeady and Shunsuke Nakamura, who share a combined total of 97 appearances.

Of the 68 actually scored by Celtic players (the other five have been own goals by opponents), McDonald (21) and Vennegoor of Hesselink (13) have provided precisely half. Gordon Strachan's fondness for dwelling on the meaningfulness of statistics, it seems reasonable to assume, should surely have persuaded him by now that the seven from McGeady, the five from Nakamura and the three each from Brown and Donati represent a very poor return from players of their general abilities.

But, in conversation before Sunday's profitable trip to Fir Park, the Celtic manager refused to countenance the notion that McGeady and Nakamura should be held culpable. He insisted that they should be exonerated on the grounds that their contribution so far was virtually on a par with last season's and that McGeady, especially, had provided more "assists" than any other player in the country.

Strachan was, however, prepared to concede that the central midfield area, where Brown's 32 appearances and Donati's 20 have yielded a mere six goals and Paul Hartley's 18 (these are league games only) have failed to produce a solitary strike, could and should have done better.

Hartley's emergence as a very proficient exponent of the primarily defensive "holding" role has clearly hindered his chances of disturbing opponents' nets as regularly as he once did, but deploying him in that position should have applied almost exclusively to European matches against high-quality rivals.

There has been a case in the past three months for playing Hartley as an attacking midfielder – in preference, say, to the disappointing Donati – in domestic matches in which the opposition could be expected to be appreciably less threatening. Hearts supporters, for example, pine for the surging, often deadly Hartley who was at the hub of the Tynecastle side who won the Scottish Cup and finished runners-up in the Premier League in 2006.

For Celtic fans, the most disturbing aspect of Brown's poor scoring rate is that he has often joked with reporters about his own shortcomings as a finisher, hinting at an acceptance of his ineffectiveness in that area as a natural and, worryingly, irremediable deficiency. A player of his energy, regularly thrusting into forward areas, should be working on completing his runs in a way that would remind supporters of the comparatively prolific Stilian Petrov.

For one of his exceptional skill, McGeady, similarly, should be more productive. Playing as wide as he does, his opportunities will be limited, but he has too often been guilty of the kind of erratic finishing that does not square with his talent.

The return to form of Vennegoor of Hesselink and McDonald at Fir Park on Sunday is surely an encouraging portent for Strachan ahead of tomorrow's showdown with Rangers at Celtic Park, but it remains to be seen whether or not the resurgence will continue against rivals who have not conceded a goal in the last four Old Firm matches.

Even victory for the reigning champions, of course, may simply delay, rather than prevent, the transfer of their title to Ibrox. As things stand, Celtic could win all of their remaining fixtures, which would include two against the current leaders, and still trail by four points at the end of the campaign.

Motherwell may have been a turning point, but it is difficult to escape the conviction that it will prove to have been too little, too late.