I cannot say about the train, since I haven't used it from BWI to the Inner Harbor area.

But, you would be really close, the only thing I don't know is how easy it is to catch a taxi from the station to your hotel.

From BWI by taxi, I always paid under $30 including tip up through last lear. It may have gone up a little since then. For the convenience, I always took the taxi from BWI to the Marriott Waterside or the Courtyard Inn near Lancaster Street. Took 15-20 minutes, and well worth it.

Adding this to the time, your arrival to your final destination in the Inner Harbor area is close either way, with a small advantage to flying in and taking a taxi. But it's not much of a diff.

At that time of night, I've never noticed any probs with traffic. At 3-5 pm, it sometimes takes 20 minutes to get OUT of the Inner Harbor area, but then it's clear sailing.

Given that there may be a game there, I would lean toward flying in/taking a taxi. I've been there on a game day, and while things are a little busy/hectic right around the stadium, it wasn't a problem. I'm thinking a lot more people may be taking the train, though, since the station is so very close to the stadium.

Just my .02, though.