Fenway Park is nearly always filled to capacity.
Of course, it is a small park, but still...
Grew up in East Boston so I remember going to Fenway as a kid in the 1970s. Bleacher seats were $1.25 and I could easily afford that with my paper route money. I’d go by myself so by the end of the game, I’d work myself through the park where sometimes I’d be sitting in an abandoned seat right in the front row. Good times.
A few years back, I took my two kids and wife to the game and spent over $300 all told.