The departure of Thomas Vermaelen to Barcelona this summer certainly left a strong defensive vacancy in Arsenal's backline for the first half of this season.

When Per Mertesacker and Laurent Koscielny have been fit, Arsene Wenger has seldom strayed from keeping faith in his two loyal defenders who have formed a solid partnership in recent years.

They're actually a very effective duo, a compliment to one another. Mertesacker is a talismanic leader who reads the game and adjusts effectively, while Koscielny employs his fluid mobility to provide what his partner doesn't. Together, they're a complete duo. Arsenal kept 18 clean sheets last season with those two working in tandem, an impressive and understated return.

However, Koscienly's inability to keep fit has thrown a spanner in the works in recent times. Wenger controversially decided to only invest in one natural centre back over the summer to replace him, and that was Calum Chambers, another Southampton hotshot who shows great promise but remains as useful as his age (he's 20) would suggest.

Mathieu Debuchy's injuries and the subsequent need for Chambers to be played as a right back has led to the heavily criticised Nacho Monreal filling in centrally. Monreal individually isn't actually that bad- the differences are more felt because that sense of partnership with Mertesacker is practically non-existent. The breaking of that partnership is the damaging component.

Partnerships take time to blossom. Which is where Paulista's entry becomes interesting. A lot of the early media attention, especially from Wenger, has focussed around granting the young Brazilian a decent amount of time to settle in to English football and adapt. Giving him a chance will mean eventually breaking that Mertesacker-Koscielny partnership, and in many ways, an injury to either of them may be the best method of Wenger achieving this.

'You always need time to adapt, especially in a defensive position because you need to know your partners,” Wenger explained. “At the moment he does not speak a word of English and that can cost you goals. If you mix going forwards with going backwards, it can cost you. It is a position where you need to know your partners and you need to communicate as well.'

'We try to teach the important words. Offside for example! Look at the linesman!'

If his time at Villareal proved anything, it's that it will take a while for there to be consistency. Speaking at the start of this season, he noted how 'last season (as in the 2013/14 season at Villareal) was new for me, a year of adaptation more than anything else. This year will be better'. And better it was.

Villareal have the best defensive record in La Liga outside Real Madrid and Barcelona and until his departure Gabriel was the only outfield player to play every game, starting 18 of 19.

Once that integration process is completed though, Wenger will fully expect his new man to challenge for a first team spot.

'He comes to be first choice,' said Wenger. 'We are in a job where competition exists and people of the moment play. Form is swinging and as well nobody is absolutely in top form for 365 days so you have to accept that'.

That will make for an interesting set of events. He certainly has the credentials to puncture what already exists.

'We look at interceptions, defensive errors, winning tackles, set piece receptions. Gabriel has good stats' added Wenger when referring to the scouting process that unearthed him.

'Of course, it is difficult to watch all the games. But what I mean is that if the numbers confirm the eye, it gives you more. If a guy comes home and says “I’ve seen a good player”, you can statistically observe this player for five, six, seven games.

'You send him again, he comes back and says he’s a good player, and the numbers confirm, you can say the risk is limited. Though there is always a risk.'

The risk is obvious, keeping his new man content and slowly easing one of his current duo out simultaneously. That may mean relegating Mertesacker to the bench soon, a similar fate to ex-captain Vermaelen.

Whatever happens, the questions that this dilemma asks of Wenger are typical day-to-day management tasks. Presumably, after-18 years in the job, that probably won't be an issue for England's longest serving manager.