To qualify for the ERA title this year a pitcher will need to throw 60 innings. The difference between a 3.75 and a 4.50 in 60 innings is five runs. Anything can happen, and it will probably be a fluke.
People also forget or ignore that the field was probably a mess. The game had already been delayed for over an hour for rain, though I'm not sure if it was raining at the time. People slip all the time on wet fields, his just happened at pretty much the worst possible time.