I went a few weekends ago, though I stayed overnight in Copley. You can drive, take the D line (Woodland is my preferred parking locations, though, I often parked at Chestnut Hill after regular working hours without an issue. The Worcester Commuter line also has a stop at Fenway now; but, I have never taken that so don't know the schedule off-hand and how effective it is. Driving in Boston is a hot mess. I would be worried about street parking as there are specific rules on game day, such as in Brookline where most areas ban game day parking. Some of BU's parking lots are also available for game day parking. Its about a 20 minute walk, perfectly safe and plenty of bars to try on the way; but, the Hancock garage on Clarendon has a discount for game day parking after regular working hours. That is typically what I do as I park there, meet friends at Pour House, which is half-way to Fenway, for pregame drinks and harassment (I'm a Yankees fan) and then go to the game. Sober up on the way back.