There's Neil Simon, and then there's Neil Simon. The West End Players Guild's recent staging of The Prisoner of Second Avenue offered America's most commercially successful playwright at both his best and his less-than-best. Thirty-one years after it debuted on Broadway, this 1971 comedy-drama about New Yorkers on the verge of nervous collapse seemed to have lost its bite and was reduced to too much bark. Then midway into Act Two, after our hero has had a meltdown, his three sisters (Dorothy Farmer Davis, Suzanne Greenwald, Eleanor Mullin) arrived to negotiate his future. Out the window went any pretense at seriousness. Suddenly the comedy was about as subtle as Abbott and Costello doing "Who's on First?" The three actresses had a ball, and so did the audience. For one scene anyway, in a story about the world run amok, all was right with the world.