Having been to several soccer matches at Rentschler Field over the years, I would have to say that it's an OK medium-sized stadium. BUT I would NOT say that it's particularly easy to get there. I've always had traffic/parking problems. Saturday was no exception. I gave myself 1.5 hours extra time to get there, and still that wasn't good enough. The local roads were so jammed we had to ditch our car at a local elementary school and walk the last 15 minutes to make it to kick off just-in-time! The turnstiles were also chaotic and slowed down entry into the stadium big time. Definitely there's a lot of room for improvement at this venue.
That's probably what it should be from NYC, but realistically it's going to be 2.5-3 from Manhattan with traffic.