Fenway has what is called the Family Friendly section - down the left field side near the Green Monster. That section does not allow the sale of, or consumption of, Alcohol. Hence "beer free" - It's something the owners decided to alleviate concerns of "fans" who wanted to bring their kids and were getting upset over the rowdy drunken actions of other "fans".
I went to the 2005 playoffs, and one of those "fans" brought their kid and made her do her homework during the game in her seat.
A winning baseball team is great to watch, but I hate the fair weather fans who show up now but who ignored the team 10-18 years ago.
You can't get a ticket at Fenway (directly from Fenway) these days unless you manage to get lucky when the tickets go on sale or through a ticket purchase opportunity drawing.
The day after I got my license, I drove into Boston with 2 friends - we went up to the ticket booth and got tickets 25 minutes before the first pitch. That's not happening today.
I only have seats to games this year because I traded the playoff tickets I was lucky enough to buy last year (through the Drawing process) for tickets to games this year from a friend with a ticket package.