The Hoops have recovered well from their European setback.
The 32-year old was taken off with 14 minutes remaining as the Hoops trailed 3-1 against Molde and he made his displeasure perfectly clear in an outburst at Ronny Deila as he left the pitch.
Celtic responded in style - with a 5-0 win over Dundee United last weekend and earned a hard-fought win at Hearts on Wednesday to ensure their progression to the League Cup semi-final – and McLeish thinks Commons' outburst may have played a part.
“The incident with Commons has probably galvanised Celtic and that is bad news for the rest of the Scottish league,” said the ex-Gers boss, in quotes published by the Herald Scotland.
“In a bizarre way, it has helped Celtic as is so often the case in football.
“He quickly apologised, scored two goals against Dundee United and the whole Celtic team are buzzing again… things like that can bring everyone back together.”
The Hoops have played some of their best football of the season in the last two games, and will need to be at their best if they are to beat Molde next Thursday and keep alive their hopes of reaching the Europa League knockout stages.
The Norwegians are surprise group leaders, with two wins and a draw from their first three games, and will be in confident mood after overcoming Ronny Deila’s men last week.