The match turned from an interesting, cagey affair to an utter farce just before halftime, when the spotlight-seeking referee Mike Dean took the opportunity to expel Arsenal center half Gabriel.
Still, let's consider these three conclusions that emerged from the encounter.
Arsenal don't have the margin of safety to buffer it against awful officiating
This is the second straight match in which Arsenal players have seen red cards. After Olivier Giroud's expulsion in the Champions League on Wednesday, both Gabriel and Santi Cazorla were sent off against Chelsea.
Like most teams, Arsenal have struggled with the subsequent disadvantage.
That's the hard--and perhaps not very revelatory--truth.
There are some interesting aspects of this reality, though. Often a team's fans will rail at unjust officiating and say that it cost their team the game, but in many cases they're just looking for an outside scapegoat for their team's inadequate performance.
In this case, Arsenal fans are right to identify Saturday's referee as decisive. And just about any reasonably impartial observer would have to agree: The unwillingness or inability to punish Diego Costa properly, the failure to defuse the Gabriel-Diego Costa confrontation, and several other key borderline calls tilted this match in Chelsea's favor.
This experience, coming just after an encounter with another inept, touchy, or easily influenced match official in Zagreb, should serve as a lesson to Arsenal's players and staff: They're likely to face injustice; their task is to minimize its effects.
Succeeding in that situation will require extraordinary intelligence, mental fortitude, and balance. It'll also take leadership, which both Francis Coquelin (a second too late) and Nacho Monreal (rebuffed by the referee) tried to exercise on Saturday. I wonder if Per Mertesaker's or Mikel Arteta's presence on the pitch would have made a difference, recognizing, of course, that Mertesacker's presence might have meant Gabriel was on the bench rather than in the heat of the action.
Now we've seen the consequences when Arsenal don't exercise the "soft skills," as opposed to the physical skills, at this highest level of performance, and they're unpleasant.
Arsenal can execute the necessary tactical plan
Before the incident that changed the match, Arsenal showed its tactical flexibility, adapting the approach to fit the occasion.
Early on, the movement of Arsenal's forwards caused Chelsea some discomfort. When that activity didn't create the important early goal, the focus shifted to keeping Chelsea at bay.
This succeeded. Chelsea had only four shots on target in the first half, and just one of those, Pedro's smothered connection with a lofted pass to the far post, was inside Arsenal's penalty area.
Overall, even with a man and then two-man disadvantage, Arsenal conceded just two of what StatsZone calls "big chances" in front of goal, the Pedro shot saved by Petr Cech in the first half and Kurt Zouma's headed goal in the 53rd minute.
The approach was similar to the one Arsenal executed in winning at Manchester City last January. Saturday had the makings of another tactical masterclass but for the referee's intervention.
Alexis needs to lift off
When Arsenal could not identify, recruit, and attract a world-beating center forward this offseason, just about everyone acknowledged that the team would need a diverse supply of goals. Midfielders such as Aaron Ramsey and Mesut Özil would have to contribute more, Theo Walcott and Danny Welbeck would need to stay healthy and be more productive, and Alexis, last season's top scorer, would have to add to his goal tally.
That mix certainly hasn't come together yet this season, and it's missing the key ingredient from Alexis.
It's not for lack of trying. Alexis ran himself to the limit on Saturday, coming off after 75 minutes. But when presented with Arsenal's one big chance of the match, he wobbled, missing the target from pointblank range not long after Zouma's opening goal.
That was Arsenal's chance to change the dynamic of the match -- despite the numerical disadvantage -- and the star man did not take it.
Whether he returned too quickly from leading Chile to the Copa America, whether his unrelenting schedule of the past two years has taken a toll, whether he just needs one shot to go in to get himself going -- Alexis needs a boost if Arsenal are to achieve their objectives.
Arsenal showed its mettle by standing up to Chelsea's bullies. The response might not have been sufficiently cunning, but we can't question the passion. Wednesday's Capital One Cup tie against Tottenham presents an excellent opportunity to channel that spirit.