Nacho Monreal and Héctor Bellerín were strangely dropped at Wembley, with Kieran Gibbs and Mathieu Debuchy taking their places.

Different people will credit different parts of the side for our recent run of form. Coquelin, Özil, Giroud have all received praise, among others. Some (strangely) even think Ospina has made a big difference.

Fullbacks as defenders

An oversight in football is to neglect the importance of the fullback positions.

Tactically speaking, they are actually vital.

Defensively Monreal has become crucial to Arsenal. As I wrote in the week, his game without the ball has come on significantly. Monreal is a more aggressive defender then ever before, and has never look as self-assured as in recent months.

Last year Gibbs got the nod and, to his credit, was probably a more solid defender than the Spanish international. He attacked the ball more often, and with a good rate of success. Not any longer.

Aerially Gibbs isn’t exactly solid. Monreal was trusted at centre-half earlier in the campaign, partly because of this.

On the other side of the pitch Bellerín is no expert, but is improving at an incredible rate. Performances against Manchester City and Liverpool have been the highlights in his Arsenal career so far.

The Liverpool game saw him booked while he also gave away a penalty, yet he shackled Raheem Sterling in the second half. The winger got the better of the young defender just once – for that penalty decision. Throughout the first half of that same game he was a key component of our pressing down the right.

Bellerín struggled at times in the quarter-final at Old Trafford, but his form has been superb. Dropping him for Mathieu Debuchy – who hadn’t started since his injury against Stoke over three months ago – was just odd.

Reading’s equaliser came from Debuchy giving the ball away before leaving too much space between himself and Per Mertesacker, which was exploited by Pavel Pogrebnyak. Gibbs was left in no man’s land by his positioning on the back post and we were punished.

Changing half a defence which has been so successful of late was a strange decision, and left us wanting a bit defensively.

On The Ball

The decision to drop Bellerín and Monreal was even more costly as we looked to get back into the game.

Firstly the obvious point: Debuchy in particular, but also Gibbs, hasn’t had much football. A huge cup game which was bound to be intense for – as it proved to be in the end – a maximum of 120 minutes was not the time to bed a player back into the side.

From 80 minutes on (and that’s being generous) Debuchy was dead on his feet. And nobody can blame him.

Taking a more nuanced view, our struggle to play out from the back was compounded by playing our two fullbacks who are our weakest technically.

Bellerín has exhibited his excellent technique during his stay in the team, none more so than when he scored against Liverpool. Monreal always has a clean first touch, and his delivery is better than Gibbs.

As Arsenal have Coquelin in holding midfield for now, there is a real struggle to play out form the back. Coquelin doesn’t show for the ball. Especially when we are chasing for a goal, Santi Cazorla is reluctant to be deep inside his own half to take the ball off of one of the defenders.

The technical proficiency of Bellerín and Monreal allow us to get around Coquelin’s limited ability with the ball at his feet.

However, at Wembley, an exhausted Debuchy wanted the ball even less than Coquelin did. He also couldn’t overlap the very narrow Aaron Ramsey as, quite simply, he isn’t fit enough right now.

Gibbs is generally a very good defender, but his ability in the final third is less than desirable. Not only does Monreal add better end product, but he’s also far more secure in possession. His first touch is cleaner, his passing is crisper.

Decisions

Wenger’s decision to change half the defence on such a huge occasion really was odd.

Regardless of opposition, the FA Cup semi-final will always be the biggest game of the season.

Playing our best defence is what we should do in big games. They aren’t an opportunity to get someone match fit, or to rest a player. Wenger has to decide who his best defence truly consists of – considering we have the FA Cup Final at the end of May. We can’t afford to have an unstable defence that day.

Every player should have to earn their place.

Bellerín and Monreal had done enough to earn theirs on Saturday, and not starting them could have been costly.