yes, 2GS proves she is champion but not the POY, for me overall performance on tour is what important when choosing POY, personally i don't like when people(players\fans\journalists\etc..) put GS above the rest of the tour, GS should be pinnacle of the tour but not the only tournament on the tour that matters
Let me try this
How many times has Serena beaten these players in 2012?
Maria, vika, Aga, Petra . Top 5 except Petra