one of the problems is if say, like last nights game, a goal is flagged offside then reviewed and given as a goal, what happens if the keeper stops when he sees the flag? or when players used to get carded for 'carrying on' when there is a flag up, does the ref still blow the whistle for the infringement or just stop play?
You never got booked for carrying on when a flag was up, you got booked for carrying on after the whistle was blown. The flag is an indicator to the referee that in the view of the assistant, a player is offside. A referee can choose to ignore it if he disagrees, it's not a decision in itself.
As regards players reacting to flags, this has the potential to cause frustration but ultimately they shouldn't, as above they should play to the ref's whistle. If you stop just because a flag goes up and the other team scores, with respect it's your fault whether or not VAR is used or otherwise.
As re the system it's clearly a difficult one and I don't really know what I think. I don't buy that people will stop celebrating goals in case they get overturned - people celebrate even though they know goals might be ruled out for offside (and sometimes are) and rugby fans celebrate tries passionately even though refs often check for incidents there after the event. In the vast majority of the time goals will stand.
The concern is the creep of VAR beyond it's remit. It should only be used for clear and unambiguous incidents:
- offsides when a goal is scored (eg. Leicester's second goal last night, the system worked perfectly),
- whether a ball has gone out of play when a goal is scored (eg. the review of a disallowed Leicester goal last night, which seemed to work perfectly),
- cases of mistaken identity (the embarrassing Oxlade-Chamberlain/Gibbs incident could have easily been avoided - these are rare anyway)
- whether a player has dived to win a penalty, or
- whether a player has commit a handball offence either scoring/preventing a goal (eg. Watford's second at the weekend).
I wouldn't even use it for whether or not was a foul before a goal as they're usually too subjective. Even handballs can be difficult but, to use the example of Watford's second goal at the weekend, there are some examples which are clear and unambiguous. If they aren't (eg. difficult debate about whether it's "ball to hand" if the hand is in a neutral position etc) VAR shouldn't get involved and it should stay with referee's call. Again with diving - if a player goes down and there's no contact whatsoever, it's obviously a dive, and VAR should step in. If it's one of the more nuanced incidents where a player appears to invite contact, but there is contact which brings a player down, VAR should stay out.
The issue is not with the use of VAR in principle, it's the application. You don't want Wenger throwing a flag to have the ref stop play for 2 minutes while an incident is reviewed.