On their previous visit to Munich two seasons ago, Arsenal suffered the indignity of only being able to name six substitutes after belatedly realising Ryo Miyaichi was ineligible. But this embarrassing defeat raised even more disturbing questions about their squad depth.
Arsene Wenger contends that, when all his players are available, Arsenal's squad is as strong as any in the Premier League. Yet, as this fantastical scenario has never come to pass, the manager's conviction is meaningless.
Arsenal have been badly hit by injuries this season, with the late withdrawals of Laurent Koscielny and Hector Bellerin taking the number of first-team absentees to nine.
But that does not excuse the club's worst-ever European defeat, particularly as the treatment room seems full to bursting on a regular basis.
And there comes a point when repeated bad luck with injuries becomes bad management - of training sessions, rehabilitation, recruitment and retention.
(Wenger's) unerring belief in some players' abilities has been shown to have been unfounded over the years, and he has also placed too much faith in a few of their bodies.
Wenger's defenders were quick to point out that no team would thrive in the absence of nine first-teamers, particularly against Bayern Munich, but even so the manager must accept some culpability for the issue.
The Frenchman's unerring belief in some players' abilities has been shown to have been unfounded over the years, and he has also placed too much faith in a few of their bodies.
It is an open secret that many at Arsenal are not the most robust, as well as being slow to recover from innocuous ailments.
It seems odd that Wenger should repeatedly give contract extensions to perennially injured senior players, such as Mikel Arteta and Tomas Rosicky, particularly when so many of Arsenal's younger assets, such as Jack Wilshere, Aaron Ramsey, Alex Oxlade-Chamberlain, Theo Walcott and Danny Welbeck also have a tendency to pick up serious injuries.
All seven are out at the moment, which is hardly a surprise.
That such an injury list should expose the rest of Arsenal's squad was also not a shock.
Five of (Wednesday's) starting line-up were in the side beaten 3-0 by Sheffield Wednesday in the League Cup last week, so if a patched-up team were embarrassed by Championship opposition, there was always the danger of humiliation against European football's form team.
Mathieu Debuchy and Joel Campbell in particular were outclassed, which is a significant concern as neither Bellerin nor any of the legion of injured right wingers are likely to be fit to face Tottenham Hotspur on Sunday.
Pep Guardiola had raised eyebrows in the build-up by revealing Bayern's intention to target Per Mertesacker, but they scarcely needed to, with the German made to look foolish for their opening goal as he appealed for offside while Robert Lewandowski was scoring his 18th goal in 17 matches this season.
Arsenal's defending was similarly woeful for Bayern's other goals, with Thomas Mueller twice, David Alaba and Arjen Robben all being given the freedom of Bavaria to score.
These are hardly new criticisms of Arsenal but, as with their manager, their players seem unable to avoid repeating the same old mistakes.
THE TIMES, LONDON