Why, why, why do Liverpool sit back when they are a goal ahead against big teams?

It's been the Liverpool way for 30 years. Take an early lead, shut up shop and then when the other team gets desperate and commits more players to attack, try and score on the breakaway...it sometimes backfires against them, like tonight and when Arsenal beat them against the odds in 1988-89 at Anfield to win the League. That's how LIverpool have done so well in Europe.