Why in Four Knights, Italian variation the winning percentage favours black after the move 4...Bc5? I was searching C46 Four knights, Italian variation at 365chess.com and here is what I found:




I am curious why 4...Bc5 gives black a slightly higher winning percentage. It seems to me that after 4...Bc5 it is white's turn to move and white should not have any disadvantage here.
As fuxia noted, winning percentages depend on how strong the players are, not just the opening. 

Think about someone likely to play the four knights as White. Since the opening is rather unambitious and fairly easy to learn, there's a good chance this player isn't very strong. I'm not trying to generalize all players here, I'm just talking about averages. Meanwhile, Black is just following the main line moves for 1...e5. This gives no indication of Black being a weaker player.

As an aside though, the 365chess database isn't the most accurate. There are way more than 3723 games played in 4...Bc5. A look at the MEGA database or TWIC would give you more reasonable stats.