I've seen alot of teams who are decent on defense, fall apart on attack easily. The main reason of this is most players, low or high elo, having not a full understanding of how defaulting works. Alot of people think that defaults are that...

I personally think both is bad to have in a game but its much more frustrating having a Teammate that clearly has no idea how the game works than an enemy smurf who Destroys you.