The pair recently returned for the Gunners following separate spells out through injury.
"We had two very difficult months and some injured players have come back which is very important for us," Koscielny told the club's official website.
"We can see with Mesut and Aaron Ramsey, it's very different [when they play] because they can make the difference. So it's important to stay like this and focus on our quality because we played well but we need to repeat these games all the time."
Arsenal are now just one win away from claiming Champions League qualification for the 17th consecutive season.