Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...f5/4. Nc3/4...fxe4/5. Nxe4/5...Nf6/6. Qe2/6...d5/7. Nxf6/7...gxf6/8. d4

8...Bg7 is a deceptive move. Yes, it defends the vulnerable e-pawn - but not by attacking the square it's standing on, which wouldn't actually work because it would still have three attackers and two (non-pinned) defenders. Instead it defends the e-pawn indirectly by allowing ...O-O, which will unpin the c6-knight and, more importantly, allow the king's rook to come to the e-file and make the white king and queen uncomfortable.

8...e4 looks impressive but it just freezes Black's central pawns into a block of ice. White can play around the block of ice with Nh4, Bf4 and Qh5, or can play c4 which hits the block of ice with a hammer.

8...Bg4 is also not as powerful as it looks, because 9.dxe5 fxe5 10.Qxe5+ breaks the pin with check, and 9...Bxf3 10.Qxf3 just gives up the bishop pair for nothing. Possibly less than nothing, as it speeds up the White queen's journey to h5.