Brendan Rodgers’ Celtic side managed to draw 1-1 Motherwell last night.
Griffiths was selected to start for Celtic, but he fluffed his lines up-front.
The Scottish international missed a spot kick and generally struggled to provide much of a threat for the Bhoys.
Griffiths was taken off in the second half, and McDonald felt that the Celtic striker’s reaction to the substitution was telling.
He said: “You can see his reaction when he came off, he wasn’t disappointed. He accepted it. He knows he wasn’t up to scratch. His penalty said everything about his performance tonight.”
Celtic had taken the lead at Fir Park when Ryan Christie found the back of the net, and they were then unfortunate with some poor refereeing decisions.
Filip Benkovic had a goal controversially ruled out, but Rodgers’ side were also guilty of missing opportunities.
And Motherwell made them pay in the last minutes when Danny Johnson scored.
Celtic’s draw saw them drop down to third place in the Scottish Premiership table, although they do have games in hands over their main rivals.