Yes, his left shoulder must have been nearer to the goal than his right foot, as he was running towards the goal. It's just cheating by Tierney and his cronies.Sterling unlucky with that offside.
They used the defender’s leg, not his shoulder for their line and I think his shoulder was closer to the goal.
Sterling’s shoulder was of course used for our line. As per usual when playing that shower, they only showed it for 2 seconds.