Bumped the thread. Against Liverpool we conceded 49% possession which is the closest (along with Napoli away(same %) we've come to not having the majority of the ball in almost two years:
I think this is right - the last time we lost possession in a match:
Premier League: Chelsea lost 3-0 at Stamford Bridge, they had 51.8% possession. 16/04/16
FA Cup: Chelsea won 5-1 at Stamford Bridge, they had 62% possession 21/02/16
League Cup: Liverpool lost on pens at Wembley, they had 61.4% possession 28/02/16
Champions League: Barca lost the match 3-1 with 65% at Etihad. 01/11/2016
Looking at Chelsea this year, I think the league stat might go at their ground (only just).