In Harry Potter and the Goblet of Fire, what dangerous diversion tactic did Viktor Krum perform at The Quidditch World Cup?

In the book, Harry Potter is watching The Quidditch World Cup. The teams competing are Ireland versus Bulgaria. Viktor Krum,on the Bulgarian team, performs the Wronski Feint during the match. Krum acts as though he sees the Golden Snitch and makes a steep dive straight down. Aidan Lynch, on the Irish team, follows Krum because he thinks he's chasing the Golden Snitch. Krum pulls out of the dive at the last second causing Lynch to hit the ground injuring himself. As a result, Lynch must be revived by a potion administered by the mediwizards. Even though this is a dangerous diversion tactic, it does not result in a foul. Later in the game, Krum catches the Snitch but the Irish still win by 10 points.