"With Lucas, you can see his confidence. We gave him the chance to grow up slowly with the team, in a country which is very different to Italy, where he had played before.
"Now we are starting to have 100% of his capacity. Bernd has integrated well with the team as well."
Arsenal sit fifth in the Premier League table and are on a 22-game unbeaten run under Unai Emery.
Emery had shoes to fill after replacing Arsene Wenger but he's a man who has impressed Koscielny greatly.
Lucas Torreira has been influential in Arsenal's recent good form (Image: GETTY)
"He's been a breath of fresh air for the club," the Frenchman said.
"He came here with his ideas of the football he wants to play. He tries to give the players all the ingredients to learn his tactics. It's very interesting."
Koscielny is back in the Arsenal picture after seven month on the sidelines recovering from a ruptured Achilles tendon.
That injury forced him to miss the last few weeks under Wenger - but worse still the World Cup.
Invalid email
We use your sign-up to provide content in ways you've consented to and to improve our understanding of you. This may include adverts from us and 3rd parties based on our understanding. You can unsubscribe at any time. Read our Privacy Policy
Laurent Koscielny recently returned to the Arsenal fold after seven months on the sidelines (Image: GETTY)
The centre-back returned in the Europa League in midweek - Koscielny played 72 minutes before being subbed off - and he could feature against Southampton on Sunday.
On his comeback in midweek, Koscielny said: "Just before you come on the pitch, you think about things.
"I had some flashes in my head of the seven months of rehab. Now it's the end of all that, and I just want to enjoy my time with Arsenal. The most important thing is to be on the field."