The Gunners came in for extra sessions following their north London derby disaster against Tottenham. Arsene Wenger's side lost 2-1 that day, falling further behind in the race for the top four, but it was the state of their defence that was cause for the most concern.
Twice Arsenal's high line was ruthlessly exposed, first by Gareth Bale and then by Aaron Lennon.
But since that humbling defeat the Gunners have kept two clean sheets. Few gave them much hope against Bayern Munich after a horrendous first-leg, but goals from Olivier Giroud and Laurent Koscielny provided them with a confidence boosting 2-0 victory - even if they still exited the Champions League on away goals.
And they followed that result with another 2-0 win, this time over Swansea in the Premier League on Saturday.
The successive clean sheets were only Arsenal's second back-to-back shut-outs this year.
And the report claims the improvement can be partly attributed to a break from usual routine when reviewing the video after the Spurs match.
Normal procedure dictates that the Arsenal players sit in on a team meeting, as Arsene Wenger runs them through the previous game's highlights.
But Wenger took the defenders aside as a separate group, as Per Mertesacker explained.
Speaking in the Daily Telegraph, Mertesacker said: "There was a lot of room for improvement and we saw a lot of things on television. Sometimes we didn't choose the right direction and we just lacked a bit of defensive work as a unit.
"We prepared ourselves for Munich and for Swansea and it was much, much better.
"We saw ourselves as a unit on the television and I think it was a good thing to do because sometimes you have a different view on the pitch and you feel different.
"Sometimes you can't believe what you did as a defensive unit. Everybody was involved and everyone felt we needed to improve and speak.
"As a unit we have to cover each other. That was the most important thing we learned. There were a lot of situations where there was no pressure on the ball against Tottenham and the back four was not prepared for any balls between us."
Since the Tottenham defeat, Wenger has also opted to "rest" first-choice goalkeeper Wojciech Szczesny, with Lukasz Fabianski taking his place in goal.