There is no conflict w/ The Indy 500 at all from a viewing perspective.
If you need to draw more viewers then you are right, Friday night is not a good idea, but lax fans will watch these games on Friday night or Saturday day time....they don't care. I don't think the viewing numbers would drop a lot....just my opinion.
Also, the issue w/ day games on Saturday is they often conflict w/ other lacrosse events. I know, since I coach 2 teams in the spring and summer. Pushing the games back gives families a chance of attending after their other events have finished.
The finals also used be at 11am to allow for more travel time back home. Having the game at 1PM doesn't do them any favors. Also, competing against ANY pro league events is just a bad idea.
The NCAA and ESPN doesn't want "lacrosse fans" to watch. They want sports fans to watch, so that those people may learn about and enjoy the game and, if not become lacrosse fans, at least be willing to watch the sport a bit more. So if you move the games to Friday night, you'll never get them on anything better than ESPNU. As for the 500, it's the same issue.
Pushing the semis to late afternoon and evening on Saturday might be better.