71k is a great crowd.
Over 20% of the seats empty is a bit shit though. Maybe the £30 seats could be made even cheaper to get them filled?
I'd probably go if it was £15.
In Berlin I went to the Olympiastadion to see Hertha play Leverkusen when Leverkusen were top. I just rocked up and paid €11.
Probably isn't the best for attracting real, atmosphere-creating fans, but then Chelsea are still doing alright with a stadium full of half and half scarves and Chinese tourists.