I did a crude analysis after the derby of % aeriel duels won as a percentile to their position in the league. Basically tmhey had 1 player in the top half (2 when Philipps came on), while our lowest was percntile 40 ish. We then brought on Iwobi, Sigurdsson & Calvert Lewin who are all 6 ft+. They brought on Shaqiri. They were completely out muscled.
I watched the 18's last night, and Onyango really came into his own in the last 30 minutes of normal time, he was just bigger and stronger than opponents.
Even our great great teams, had Van Den Hauwe at fullback, Grey and Sharp through the middle, Mountfield who was very good in the air at centre back. Unless you are a world class team, as City are, it has to be a big factor. Having height, and delivery will get you over the line in tight games that could go either way.