Possibly. Maybe not that straightforward though, i don't remember goalkeeping errors being particularly to blame for them losing points off the top of of my head. However, they scored 1 goal less than city, but conceded 13 more, and conceded the second highest amount of goals in the top 8 behind... well us of course. So its definitely true they could do with keeping it tighter at the back... how much of that was Mignolets fault though, considering their defence was bang average is debatable. They had a league champions attack and a relegation battlers defence.