Is the Grand Prix Attack a poor response to the Sicilian? The Grand Prix Attack begins 1. e4 c5 2. Nc3 Nc6 3. f4. It is an anti-Sicilian for white that is popular among club players because playing it requires memorizing significantly less theory than the open Sicilian. However, I wonder if playing it is a good choice. 

According to the 365chess database, after playing 3. f4, white wins 36% of the time, while black wins 40% of the time. That is, by playing 3. f4, the white player seems to give black a slight advantage. Compare this to the open Sicilian or the 2. c3 Sicilian, where white maintains a slight advantage in winning percentage. It is tempting to conclude that white should not play the Grand Prix attack, and instead choose another anti-Sicilian. The large sample size (11,000 games) seems to indicate that playing 3. f4 really does put white at a disadvantage, and that the winning percentages aren't just a statistical anomaly. 

It's not hard to come up with an explanation. Moving the f4 pawn seems to give white a slight structural disadvantage. If white can't strike the killing blow and black can close up the game, the weakened kingside allows black counterplay. 

Certainly, one can easily think of objections to this analysis. For example, the games in the database are not a random sample, and there is probably a large bias towards 2000+ level play. And it's true that at a club level, especially below 1600, tactical blunders in the middlegame are going to make the opening moves irrelevant. But the sample size is huge, and the effect is significant (a 4% advantage in winning percentage for black, instead of the usual 3% advantage for white in the open Sicilian). Why not play it safe and choose a different anti-Sicilian? I don't think club players should hamstring themselves unnecessarily. 

In light of the above, are there any good reasons for club players to play the Grand Prix Attack instead of a different anti-Sicilian? For example (and I don't have the computational skill to do this, otherwise I would), do the winning percentages look different for sub-2000 players?
I don't have any statistics to back this up, but many openings where black has a large plus against white it isn't necessarily because the opening is actually so bad that it gives black a significant advantage, but because the opening is more popular at a lower level (which is normally because it actually is worse than other openings) so the players who play it are on average lower rated than their opponents and would most likely score less than 50% anyway. 

Normally the openings with low percentages for white are slightly worse than other openings for white, but not necessarily so bad as to give black the advantage, but then the fact that they're worse than others kicks in and the higher level players play them less often, leading to that opening to score a lot of losses for white, even in a game which is even or with a slight edge for white after the opening.