There's no way that was a sending off. McArdle and Langfield were both between the forward and the goal. I can't understand why the Kilmarnock defender wasn't sent off for giving away the penalty.
Blackman doesn't run off the ball, he doesn't take up goal-scoring positions, he's not strong, he doesn't hold the ball up, he can't beat his man.
He just looks like a lazy waste of space at the moment.