Arsene himself said "Mikel is very popular with this team mates and they all respect him". Vermaelen was kept out of the side by a very consistant prtnership that lose something like 1 game in 40 games together (90 minutes) not to mention that he was struggling with injuries (he is out injured from the WC) so i wouldnt say the manager was ruthless or anything like that, Kos-Mert made his mind up for him.'
Arteta is the best DCM we have and thats why he starts but thats mainly because the only other option is a washed up Flamini.