Nacho Monreal and Cesar Azpilicueta are surprisingly similar so it’s no wonder comparisons are being made.

At a cursory glance, you may notice that Monreal and Azpilicueta are both Spanish and are both full-backs.

However, the similarities don’t end there.

As pointed out on Pain in the Arsenal, both players have had remarkably similar career paths: both moved to England from Spain, both started as full backs for their teams, and both ended up as an important centre back in a back three.

This may not be as much of a coincidence as it appears.

Monreal and Azpilicueta fulfil a specific role in the Arsenal and Chelsea teams as a left-sided centre back and a right-sided centre back respectively. A defender in those positions is often exposed to opposition wingers due to the attacking nature of the wing back role, and is forced to defend in wide positions on top of defending the centre. Hence, it’s important to have players who are comfortable doing both.

Full backs playing centrally isn’t a new development, but the increasing importance placed on attacking full backs has reduced the popularity of the old-fashioned defensive full back.

However, the resurgence of the back three in top level football has given the defensive full back a new lease of life. Who better to play those side-centre back roles than wide defenders who know how to defend?

That Monreal and Azpilicueta happen to be defensively-able full backs can be attributed to their identical schooling. Both players emerged from Osasuna’s academy and played in the same team on either side of their defence.

Neither player grabbed the headlines.

Monreal made a quiet move to Malaga in 2011 and took part in their Champions League adventure, while Azpilicueta remained at Osasuna for another year before making the move to Chelsea. Monreal joined Arsenal six months later.

It took some time for both players to be appreciated. It wasn’t until Azpilicueta was playing left back for Jose Mourinho’s title winning Chelsea team during the 2014/15 season that people began to notice his contributions to the team.

Monreal, meanwhile, was known as a solid, if unspectacular, performer at Arsenal. It wasn’t until his shift into the middle of the defence that fans began to notice his defensive qualities.

Now 31, the positional change has come at the right time for Monreal.

He may soon not have the legs to get up and down the left flank as he used to, but is now in a position where he can use all his intelligence and experience to help the team.

Just as Azpilicueta became a vital part of Chelsea’s back three, let’s hope that Monreal can do the same and help Arsenal to the same on-pitch success.