His injury problems are overblown, he played 38, 46 and 43 games in the seasons before his big injury last year. To put that into context, Koscielny has played 34, 46 and 36 in his last 3 season.
Anyway, I'm not suggesting anything other than the fact that he at the very least should be part of the discussion, he finished the season as our first choice and has 7 goals in 7 starts.