To be honest, if traced properly, they have players who are quite capable, and with the quantity of players that can be relied on but unfortunately they do not have a strategy that can really penetrate the middlesbrough defense.
But we also need to remember that Chelsea indeed when against strong teams they will also strengthen but when against teams below them, sometimes they play with poor performances, but maybe the second round they can get a victory and avenge the annoyance they get for the embarrassing 1-0 defeat.
People still gets disappointed from Chelsea performance, I have remove them since first week of December from my favorite teams for gambling. I don't pick them to win and I don't their rival to win because I don't know them again. The last time I check their standing on the table was the same early December and I check and then they remain where I left them, 8 win 8 loss and 4 draw, damn Todd Boehly is a calm man. If I'm the owner, my hot temper would have sent him a sack letter to live my fucking club for his incompetent.
How can you have 70 ball possession and can't make a simple chance, all their shot on target were useless and conversion was poor. Been in Premier League is a privilege and hardwork, when a team of Premier League has a match from another team from other leagues, it shouldn't be ground breaking thing to do, more like a soft work but Chelsea made it look like impossible miracle. Maybe the next time they start having less fans coming to watch the team matches, the owner will become proactive person.
Pochettino is the person most responsible for the results, now many fans are asking him to resign as head coach, and I think if Abramovich was still in charge of the club, Pochettino would have been fired last year. Everything is pointing towards setbacks, there is very little we can be proud of about Chelsea this season. Their performance has been a roller coaster, so betting on their win would be a disaster.
Not appearing in European competitions does not change anything, in the sense that he can't be used to compete in the title race, a fact that makes the fans reaction very disappointed. Perhaps the only understandable reason why the Blues have performed poorly this season is their aggressive transfer policy, building a squad with young players and not managing the transition well. The rest are just factors that are generally experienced by all clubs, such as injuries and so on.