The Cards play on grass (Unlike the Ravens and Bengals who play on grass no matter where they are) and The Bengals and Patriots play on artifical turf.
So that’s 15 out of 32 which is nearly half.
So much for trusting answers.yahoo.com
Anyway, the point stands. “Most” means more than half which means 17 teams would have to play on the fake stuff for this author to be correct.