Complex sentence: It is important to understand that the irregularity does not happen after Fabregas assist (which eventually led to the goal), but after Torres's cross offsided Iniesta ran towards the ball causing van der Vaart to intercept it.
Split into simpler sentences: It is important to understand that the irregularity does not happen after Fabregas assist (which led to the goal). After Torres's cross, offsided Iniesta ran towards the ball causing Van der Vaart to intercept it.