For the last few years the tackle from behind has been outlawed. The exception to this is if the tackler gets the ball cleanly without first contacting the opponent. The rule was brought in to prevent the argument 'I got the ball' when the Savages and Bartons of this world had studded the back of a knee or broken an ankle in order to achieve same.
Referees have been required to interpret this rule and have been slightly lenient if there is a minimal 'brushing' contact and the ball is taken away from the opponent completely.
And so to last Tuesday's Champions League semi-final second leg between Arsenal and Manchester United. Fabrigas through on goal and Darren Fletcher comes from behind to tackle him. Does he get the ball? Yes, but he doesn't push it away from danger, simply prods it a little to the side. Does he touch Fabrigas before he gets the ball? Yes. Slightly? No, he has his hand on his shoulder pulling down and his thigh against Fabrigas' thigh affecting balance. Fletcher then continues to tangle with Fabrigas until both fall to the ground although Fletcher was out of the game once he committed to that tackle and Fabrigas could have continued to try and score.
Red card? Yes. Quite right. Stupid tackle. Daft decision to make it. Great decision from the referee who had no choice. Does it make any difference that Manchester United were 4-0 up at the time? No. The rules of the game don't change when one side seems certain to win.
Stop pleading Fletchers case.