Koscienly arrived in North London in the summer of 2010 to little fanfare. Many believed that the player, who had spent only one season in French football's top flight, represented a poor answer to the Gunners' defensive frailties.
However, the former Lorient standout has confounded his critics and swiftly developed into one of the more accomplished central defenders in world football. Koscielny has overcome some early struggles of adapting to the rugged nature and frenetic pace of the English Premier League.
The 2011/12 season was a breakout campaign for the 26-year-old. He was easily Arsenal's best defender and is quickly becoming the kind of linchpin that a strong defense can be built around.
Under Wenger's tutelage, he has gone from being just another unheralded French prospect to becoming a full-fledged international. Koscielny's rapid rise proves that Wenger is still as astute as any manager at the top level when it comes to identifying and developing talent.
As recently as 2008, Koscielny was plying his trade in France's Ligue 2. Yet Wenger's selection process always emphasises the long-term potential of a player. A look at Koscielny's playing style offers a key indicator as to how Wenger allows players to flourish.
The strengths of Koscielny's game are intelligence and anticipation, particularly in one-on-one situations. He is a ball-playing defender, both in winning the ball and using it.
In the robust environment of the EPL, where forwards are only too willing to apply constant pressure on the ball, that kind of style can often land a defender in trouble. However, Wenger has allowed Koscielny to stick to his preferred mode of playing.
Thomas Vermaelen has been charged with winning the aerial duels and providing a physical presence. This allows Koscielny to use his superior technique to intercept and sweep up attacks. In typical Wenger fashion, he has emphasised a player's best points, rather than forcing him out of his comfort zone.
Wenger's knack for transforming raw potential into established, top-level talent will be key to Arsenal's future, given the finances at other clubs and looming rule changes. At a time when his transfer policies are being aggressively questioned by fans, pundits and even his own players, Koscielny shows that the Wenger model can still work for Arsenal.