I disagree about the 1st degree murder charge. That will be almost impossible to prove. The kid did not go there with the intention of killing the victim. This should be 2nd degree murder or manslaughter. I think the punk will walk because they overcharged. Maybe deliberately, to let him off.
In Texas, capital murder is equivalent to murder 1 in many other states. Murder 1 in Texas is equivalent to murder 2 in other states, etc. The investigation is still in the early stages. There are eye witnesses and likely some cellphone videos of the murder. I would think there would also be some stadium security surveillance videos.
You charge on the weight of what the evidence tells you in the short period from the evil act to arraignment.
To date, the evidence is a spread between Murder 1 and Murder 2:Sudden Passion.
As a DA, you're obligated to take your best shot -- what if the DA had only filed for Murder 2:Sudden Passion and Manslaughter -- you'd be bitching about that!