Only Arsenal manager Arsene Wenger will know exactly why he opted to begin the season with just three recognised centre-backs; one of whom was a teenage summer signing whose Premier League experience had come playing as a right-back.
But whatever the reason, the Gunners are now suffering as a result, and their opponents are relishing the prospect of coming up against a side who look porous at the back in the absence of the injured Laurent Koscielny.
Against Swansea City on Sunday, Wenger opted to keep Nacho Monreal at centre-back despite the Spaniard clearly adding a huge air of uncertainty over a back-line that once prided itself on its stability.
Not anymore, with Arsenal again throwing away a lead - although this time only a single goal - to lose 2-1 at the Liberty Stadium.
Questions have to be asked as to why Monreal was picked to start against first Wilfried Bony and later substitute Bafetimbi Gomis - two of the most physical front-men in the top flight; especially when he has shown in previous encounters that his presence at the heart of the defence could well lead to chances, and goals, for the opposition.
The most telling statistic on Sunday can be seen below, with Monreal failing to win a single aerial battle - a damning stat for a centre-back...even a makeshift one.
|Passing Accuracy||Tackles Won||Duels Won||Aerials Won||Interceptions Won||Effective Clearances||Mins Played|
Why Calum Chambers was not played alongside Per Mertesacker and Hector Bellerin chosen at right-back is another mystery. At least the former Southampton player has experience playing there and is far more dominant in the air.
But instead Arsenal were punished for what can only be deemed a poor (and baffling) decision.
Surely Wenger will not make the same mistake again; except of course that the same could have been said just a few days earlier.