Have you noticed this?

[nikvoodoo]

I think the bloodsport theory is pure Hoowee! Nothign supports it other than Sam being dragged to the center and lasting long enough to scream twice.
1. So, This begs the question of why do they kill if they're able to digest and are interested in "People food" *no pun intended*
2. What does this mean evolution wise?
3 How the hell can they tell what's food if it isn't running from them? Smell? Sight? Memory?

1. Why does a Grizzly Bear eat fish and then also eat berries? Because it can.
2. Honestly, it means nothing in terms of evolution. Unless you are a vegetarian or vegan, you are already an omnivore. Human beings eat anything they can. Perhaps our zombified friends simply lose their ability to taste and will consume what ever they come across.
3. We know they have super human olfactory abilities. I'd assume they go by smell. That's how they eventually found the MRE's. Skittles ate them in the supply warehouse. Before that, nothing could smell them.

And I still support blood sport because Samantha says they play with their food before they eat it. Is it still a long shot? Yeah, but I like the idea of it.