It's not going to stop it though is it. Was laughing at work the other day about how illegal streams have better quality picture and continuity than the paid for ones. NowTV for instance isn't great. The TV players are terrible. Not that I've ever watched an illegal stream officer, so not sure I can comment.
As for putting these people in prison, there are other criminals far more worthy of locking up in my opinion. Anyone who harms the general public should be locked up - simple as. The best way to sentence people like this is to remove any way of them using technology. I'm not sure how you could do that but it would be the proportionate punishment.
The only people served by jailing these, are the Premier League and the companies paying for TV rights. As they are all generally money grabbing scum fraudster themselves, this is not in the public interest.
Plus, as I stated in the first sentence, this won't stop.

Red and Blue Army!