The bare facts are these: Fletcher complained to the referee that he was "..constantly being fouled.." When he said something to the official, Clattenburg dismissed his complaint with the phrase "It's a man's game.." Fletcher said that he then "..went in hard and he books me!" He was cautioned before half-time for the foul, and observers did note that Fletcher continued to "..bait.." the referee and received a "..final warning.." early in the second half. Finally in the eighty-fourth minute, ".. he cynically tripped the Birmingham player," said Clattenburg, and out came the red card. Was justice served, and could the dismissal have been prevented?
It's difficult to be tolerant of a player's constant complaining, like some obnoxious harridan in a fish-market, but referees must always seek to understand what contribution their own behavior might have made to the situation. Certainly, the official should neither bait nor goad a player into doing something foolish. I do know of one case years ago, when an upset referee followed a player around the field urging him to do something stupid so "..I can send you off!" The terrified player, not surprisingly, was afraid to go near any opponent.
So Fletcher comes at the referee with complaints about being fouled. The most tactful response would be something like: "Well, if I call it tighter, it's going to go both ways. Is that what you want?" But the response that Clattenburg chose was combative, suggesting with his answer that Fletcher was not man enough to play the game. No diplomacy there, and it was no surprise that Fletcher went immediately and clattered a Birmingham player. You can almost hear him say: "Well I'll show you, mate!"
Fletcher came to the referee angry, and left even angrier. He kept on complaining and you can imagine what was going on in Clattenburg's mind. Is he never going to shut up? So instead of soothing a situation, the referee aggravated it, and the red card became inevitable, as Graham Poll deduced. Clattenburg had reached his limit, and I'm guessing from similar personal experiences at this level of play, that he had lost any interest in pacifying his tormentor. The opportunity for using wiser words was gone.
Rudyard Kipling comes to mind: "If you can keep your head when all about you are losing theirs and blaming it on you . . ." You probably know the rest.