John Stones offside? The reason why Man City goal was allowed to stand vs Arsenal | OneFootball

There was controversy surrounding Manchester City's second goal against Arsenal during their huge title clash.

Kevin De Bruyne had given City an early lead in the seventh minute, placing the ball beautifully past Aaron Ramsdale.

It was a first half in which Pep Guardiola's side dominated.

However, it looked as though they would be going in at half time just one goal to the good.

That was until De Bruyne curled a beautiful free kick onto the head of John Stones, who powered his header past Ramsdale.

But the assistant referee raised his flag immediately and the goal was disallowed.

Replays appeared to show the assistant referee had made the correct decision.

After several minutes of deliberation, though, VAR awarded City the goal stating that Stones was, indeed, onside.

Really!?

Further images showed that Arsenal defender, Ben White, may well have been playing Stones onside with his foot.

But why did it initially look as though Stones was well offside before the goal was awarded?

Well, VAR expert Dale Johnson, explained all in his VAR review on ESPN.

Why Stones' goal was given despite appearing offside

Johnson wrote: "It [Stones' goal] caused a great deal of discussion, but it all comes down to parallax: the difference in the apparent position along different lines of site. It's one of the main reasons the offside technology was introduced, to remove the problem we have in taking a picture and processing it as a 3D image. As different angles are checked, moving left to right across the pitch, parallax means the position of Stones relative to Ben White will appear to change.

"From the main television camera angle, it seemed certain that Stones was in an offside position; when the VAR switches to the goal-line camera, the decision is going to be much closer.

"The VAR isn't choosing an angle to best produce a particular outcome, he chooses the one which gives the best representation of the decision -- one which all relevant body parts can be seen.

From the first camera angle, we presume Stones is offside because the position of the City's players upper body; White's foot cannot be seen.

"Offside decisions are made using synced cameras. The kick point -- this is the first frame which shows a touch of the ball by the passer, and not when the ball leaves the foot -- is essentially frozen on all cameras. Sometimes the ball may not appear in the offside image, but the kick point has already been set using all cameras stopped at exactly the same place.

"Because of the possible issues about accuracy around the kick point, the offside technology has a tolerance level built in (if the two offside lines are touching.) Essentially, this creates a "benefit of the doubt" for an attacking player when the decision is very close. Stones needed this for the goal to be allowed.

"When this tolerance level is used, the final VAR image only shows one green line to the defender (the method is the same in all leagues), because showing both lines on top of each other would be more confusing.

"It's not perfect, as it means supporters must trust the line has been placed on the correct place for the attacking player.