The first three are the old or sick; they set the pace for the entire pack. If they weren’t at the front they’d be left behind and would lose contact with the pack. If the pack is ambushed they’d be sacrificed.
Then come five strong ones, the front line; in the centre are the rest of the pack members; finally the five strongest.
Last is Alpha. He controls everything from the rear. In that position he can see everything, deciding the direction of travel.
The pack moves according to the elders’ pace and they help each other; protecting each other.