I don't know if I'm just missing it but when looking at team stats, I don't see
any for defensive statistics such as rushing yards allowed per game, passing
yards allowed per game. Could these please be added if they aren't currently
calculated.

Go to the league home page, you'll find them there. Yeah it would be handy to have them on the team page though.

Actually it is on the team page - click on the "stats" tab, you see the player stats, but there's another sub-tab "team stats" that lists the same stats that are on the home page except just showing your team.

Ha ha, I didn't even see that, the text level is so subtle, maybe a bit bolder for us older folks?