At the start of the season Nacho Monreal was seen as a bit of an outcast. Kieran Gibbs had been given the number 3 shirt, left vacant by Bacary Sagna, and looked to have that left-back spot nailed on. Monreal was seen as a back-up centre half due to the limited options in that position but over recent months it's been the Spaniard, rather than the Englishman, that's been impressing the most at left back.
Previously Monreal has been a replacement for when Gibbs has been injured. However that has seemingly changed in 2015 after a string of solid displays from Monreal. Despite that, Kieran Gibbs has still been called up to the latest England squad for the games against Lithuania and Italy, that's even with the vast amount of options Roy Hodgson has at his disposal in that area of the pitch. That just goes to show how good of a dilemma Arséne Wenger has in terms of who he utilises at left-back for the rest of the season.
When Monreal joined Arsenal it was clear from the offset that he would provide brilliant competition with Gibbs. He had already won a number of caps for Spain and had good spells at Osasuna and Malaga in La Liga. Albeit the number of appearances that he's earned for his national side has sadly not improved as much as he would have liked. Perhaps with his renewed form he could well work his way back into the Spanish side though. The fact that Monreal is now ahead of Gibbs in the pecking order after a troublesome period last campaign is encouraging for Arsenal fans to see.
Kieran Gibbs was Arsenal's first choice left-back last season and also at the beginning of this campaign when fit. However Monreal's spell at centre back earlier in the season has improved his game heavily. The Spaniard has toughened up and defensively he's a lot better than he was. Playing in the centre rather than outwide has seen him develop an aerial feature to his game that wasn't necessarily there before. The amount of aerial duals Monreal has won have become significantly greater, winning 60 duels in one more League game than Gibbs whose won 27 (before Newcastle game). Nacho Monreal meanwhile looks more assured against someone when they try to take him on and he's become more solid than he has been in previous seasons. Such is his form that since the Southampton game in January only once has Gibbs started over Monreal in the Premier League; the 2-1 win over QPR.
Wenger's dilemma is an interesting one though. Kieran Gibbs offers more in attack and looks to get to the byline, therefore offering more support to Alexis Sanchez and also offers options in behind and on the overlap. Monreal however has a more conservative approach to his game. He does go forward, and that was displayed with his goal against Manchester United in the FA Cup and his role in the second strike against AS Monaco in the week. Since the 2-0 win over Manchester City at the Etihad though, a more assuring Monreal is evident. He's a lot more disciplined in his approach to the game than he has been previously and that suggests why he's been starting ahead of Gibbs.
Hector Bellerin's rise to prominence has also played a part in terms of why Kieran Gibbs isn't starting. Monreal and Bellerin offer the perfect balance of attack and defence between them in the full back role. Bellerin gets forward more which means Monreal tends to hold himself in the middle of the pitch when Arsenal go forward. Both Gibbs and Bellerin starting offers an imbalance though. An imbalance that proves crucial when playing the bigger teams. For example in the first leg of Arsenal's Champions League tie with Monaco, Wenger played two attacking full-backs in the form of Gibbs and Bellerin. Consequently, The Gunners were punished for leaving too much space in behind for their opponents to exploit.
It goes without saying though that Monreal did endure a very sticky spell last season. He was known for being a defensive liability but it's a testimony to the way he's bounced back that he now finds himself as a valuable reason for why Arsenal are in such great form domestically. The Spanish international is now a crucial part of Arsenal's defensive line but for Kieran Gibbs it represents another challenge for him to overcome. Gibbs has previously been stuck behind Ashley Cole and Gael Clichy when they were at Arsenal whilst he's also had to deal with persistent injury problems throughout his career. However he now has to find the defensive qualities in order to work his way back into that left back spot, rather than coming off the bench like Monreal did for the majority of 2013/14.
With such a crucial run in towards the end of the season it should see both players become invaluable in terms of offering each other rotation options in defence. After all, both Monreal and Gibbs offer reliable services at left-back and present Wenger with a very nice dilemma to have when selecting his team.