The first three in front are old and sick,they walk in front to set a pace of entire pack and they will not be left behind;
The next five are strongest, fastest and most ferocious, they are tasked to protect the front side in case of attack;
The pack in the middle are always protected from attacks;
The five behind them are also among strongest in the pack, they are tasked to protect the back side in case of attack;
And finally the last wolf is the LEADER. He ensures that no one is left behind, he keeps the pack unified and on the same patch, he is always ready to run in any direction and protect, he serve as "bodyguard" to entire group.
Being a LEADER it is not about being in front, it is about taking care of your team or in this case pack.