Pegging in an unconstrained plan

Item ABC has 476 pieces on hand. If you check into pegging this on hand pegs work orders with start dates out until 24-feb-2017.

There is a firmed work order for item ABC. It has a suggested completion date of 16-FEB-2017 23:30:00  If you check into pegging this supply it begins pegging to work order demand with a 15-Feb-2017 date

Why wouldn't the on hand picked this up to peg to rather than extending out to the 24th date?

thanks in advance