Make sure you pre buy your Harpoonfest tickets and get there early. I went to meet my friend for the spring fest and the line was probably a half mile long.... no joke.
And as for me, I just departed Boston last week and am in the process of moving to Cali... or I would've met up with ya.
If you go to Game On, the Buckeyes are downstairs. Don't drive there...take the greenline and get off at Kenmore, go towards "Fenway" take a left out of the T station and then follow the crowd to a left on the first street. Game On will be on the left side.
I've gone during Red Sox games and it's just a bit more crowded, but if you get there by say 6:00pm you could put your name down for a table or find a bar spot. It will start mildly emptying out right before game time.... and then slowly fill up again during the night.