From reading this it doesn't seem like Hayes should get off free, but more like the prosecutor overcharged it and relied on the statements from folks hell bent on protecting Will Smith's legacy than telling the actual truth. His wife and Hernandez make this whole shyt look suspect.
That said, Fuller is doing a master class right now of breaking down witnesses while also building a separate narrative. It looks like his plan is the make Will and Hernandez look like the aggressors and he started by consistently bringing up how Hernandez was aggressive meanwhile Hayes and his boy didn't even run after the whole thing went down. There's a whole lot of "I don't remembers" flying around from everyone in the Mercedes. The wife specfiically saying Hayes was loud, angry, and evil looks dumb as fukk when the off duty cop comes up and says how calm he was and same with the neighbor.