What makes GSP such a good wrestler in MMA prehaps wouldn't work in a pure wrestling match. It's his ability to threaten with punches and then switch levels and take people down, his explosiveness surely helps too.
And that is also a John Jones asset. Guy can hit you anyway he pleases from any angle using any body part and when he decides it's time to you to lay on the mat, you will lay on the mat. That's MMA wrestling at its finnest application and it doesn't matter he lackes the pure wrestling credentials of many other fighters.