It’s unusual for Arsenal to recruit two players in the same position within one transfer window, but the double signing of Mathieu Debuchy and Calum Chambers means Arsene Wenger has replaced the departing Bacary Sagna with quantity, as well as quality.

The thinking is obvious - one for the present, one for the future. Top football clubs must possess two top-class footballers in each position; ideally one providing experience and guaranteed quality, another playing understudy and learning his trade.

In Debuchy and Chambers, 29 and 19 respectively, Arsenal have followed the template perfectly.

Debuchy was the obvious replacement for Sagna - after all, he was keeping Sagna out of the France starting XI at the World Cup. He arrives after an 18-month experience at Newcastle, following a decade in Ligue 1 at Lille, so should be up to speed with the demands of English football.

"He's sharp in his marking, good with interceptions and quick to go from defence to attack. You feel he always has the desire to go forward. I believe he will be perfectly suited to our style" Arsène Wenger on Debuchy

Debuchy is an interesting right back - at his best, he’s a great all-rounder who mixes modern attacking full-back play with a touch of traditional, old-school defensive work. “I think he's very good going forward, he's very quick in transition,” says Wenger. “He's sharp in his marking, good with interceptions and quick to go from defence to attack. You feel he always has the desire to go forward. I believe he will be perfectly suited to our style.”

Debuchy is capable of galloping down the right flank and swinging crosses into the box, with a good change of pace and an intelligence in the timing of his runs. He collected three assists in the Premier League last season, a good number for a full back, and will hope to recreate Sagna’s good relationship with Olivier Giroud, in terms of near-post crossing.

Equally interesting, though, is Debuchy’s defensive work. In the modern game, many full backs defend properly only when attacks come down their flank. Debuchy, however, is very diligent at covering for his defensive colleagues when the ball is on the opposite side of the pitch, often sweeping behind his own centre backs if they’re beaten.

Debuchy is also excellent in the air. Although this isn’t generally seen as a key component of full-back play, Arsenal depended upon Sagna’s excellent spring, particularly from Wojciech Szczesny’s goal kicks. Debuchy is the only full back in the Premier League who won more aerial duels than Sagna in 2013/14 - four per match, with a success rate of 70 per cent.

Debuchy played just once against Arsenal last season, missing Newcastle’s 3-0 defeat at the Emirates through injury. But he showed his all-round ability in Newcastle’s 1-0 defeat to Arsenal at St James’ Park, and his defensive contribution was particularly obvious.

This chalkboard (Fig 1) shows the advanced position of Debuchy's interceptions (blue), his tackles in the right-back zone (green), his clearances in more central positions (purple) and his goal-line block from Theo Walcott’s effort (yellow).

Fig 1 Debuchy defending v Arsenal

But he was also an attacking force. Debuchy specialises in arriving late and unmarked at the far post, and he caused Arsenal problems in this respect.

Mathieu Flamini was fortunate not to be penalised for fouling Debuchy in the box, and the right back had two decent efforts at goal. One was from open play, the other was a header from a corner which hit the bar.

Fig 2 Debuchy attacking v Arsenal Chambers is a more versatile player, with Wenger admitting he’s hoping to utilise him in a new role, as well as his traditional position of right back, where he rotated with Nathaniel Clyne throughout Southampton’s 2013/14 campaign.

“He can play at centre back, right back and central midfield,” says Wenger. “I hope he will give us competition for the players in these three positions.”

"I hope [Chambers] will give us competition for the players in these three positions" Arsène Wenger on Chambers

The most obvious thing about Chambers’ skill set is his raw technical quality. He’s extremely capable in possession, a fine passer and able to dribble forward solo to turn defence into attack smoothly - there’s great composure about his game.

His pass completion rate last season was higher than Debuchy’s, partly as he played in a more forward-thinking, technical side.

Chambers is also a quick player, however, and at such a young age it’s understandable that he’s been deployed in a role where scampering up and down the touchline is his main duty.

Like Debuchy he can whip crosses into the box, although he’s also capable of intelligent, more measured passes into attack.

Chambers' performance against Arsenal in the 2-2 draw at St Mary’s last season was encouraging. His interceptions (blue) took place in a similar position to Debuchy’s, but his tackles (green) were out wider, near the touchline, and his clearances (purple) were in a horizontal line, deep inside his own half.

Fig 3 Chambers defending v Arsenal

Clearly, both players impressed Wenger when he saw them in person, and they’ll be hoping to do something similar over the next couple of weeks.

With the Emirates Cup this weekend and the Community Shield the following Sunday, both players should have opportunities to show their quality before the start of Arsenal’s Premier League title charge.