I have to disagree with this. Screen grab of the offside below. The offside itself is quite tight so I can understand (given the current application of delayed flags) why the lino didn't flag straight away. Also, Lavia wasn't injured in the melee. He gave the ball away initially in Chelsea's half which allowed them to start the counter, started sprinting back, during which he pulled up and started feeling the hamstring. In the image of the offside you can see him holding the back of his left leg.