Simon proved to be the key, in a negative way then, in this Davis cup tie.
As much as I admire Simon for his tenacity, he simply does not have the game of fellow top players. When in a match where the opponent really wants to win: i.e. Grand Slam or Davis Cup, it gets tough if you can't win on your own terms. Simon depends on the weaknesses, especially mentally, of his opponents. This pays him handsome dividends in smaller tourneys and even in Masters series, but in a best of five, playing for the honour of your country, opponents will always have a little bit more backbone.
France should have opted for Monfils IMO. That is off course very easy to say afterwards.