Well the Sp Atk is 4 because it is hindered by the Jolly nature.
The Speed is 6 because it is boosted by the Jolly nature.
The Defense is 7 because naturally Skorupi has a high base defense of 90!
The defense stat may also have good IVs. You can check IVs by talking to a man in the Kiloude City Pokecenter.