A somewhat balanced approach. Your Bloodthirster will be Blitzing every turn and getting 6 Dice hits, so should not suffer many turn overs. It will also rack up SPP fairly quickly as a result, so getting Juggernaut or Block to make them even more reliable will not take long. This roster stars with an extra player which is needed, as you will cause damage to your own team mates and suffer attrition at the hand of your opponent, who will likely target the Linemen and try and stay out the big guys way. 2 Bloodletters gives you a little extra pitch control and punch. But you will need to be careful about when you activate them. Their Frenzy also narrows the opposing screen. 2 Re-rolls is tricky to manage, but as your Blitz is pretty reliable the Re-rolls are for key Blocks from your linemen or for dealing with the ball in key moments. You should be able to get by with 2.

The conservative/boring/min max approach. 1 Bloodthirster, he does all your hitting. 3 Re-rolls keeps your Linemen fairly safe with blocking and picking up/handing off. Starting with 3 dedicated fans should be enough... you can take more if you wish, but having a little money saved over, so you can get extra players or possibly Bloodletters asap is useful.

The maniacs approach: This is not really recommended, and is something of a meme build. But it is possible to make it work. Between your 5 Bloodletters and your Bloodthirster you have similar pitch control to a Lizardmen team. Your Bloodthirster is also getting 6 dice most of the time on their Blitzes which they will be doing every turn... You have 1 on the bench which is good protection for the inevitable self inflicted hits. Just keep your fingers crossed when you pick the ball up. Also try not to active the letters, just leave them as a screen. All that St4 is a real pain for most teams. No re-rolls is obviously a bit crazy... so getting praying to Khorne and Nuffle.