Earlier I said that there isn't much difference between Hayden and the likes of Tendulkar, Lara and Ponting and yet I put Hayden a barrier underneath them; likewise with the Pietersen & Sehwag scenario, with Sehwag being only one barrier beneath Pietersen. I'd range the classes between players like this:
Top Class (Obvious Alltime Greats): Tendulkar, Lara, Ponting, Steve Waugh
2nd Class (Arguable Alltime Greats): Hayden, Kallis, Dravid, Pietersen
3rd Class (Quality Players, Not Alltime Greats): Sehwag, Gambhir, Inzamam, Chanderpaul, Hussey, Sangakkara, Smith, Flower, Thorp, Kirsten
4th Class (Inbetween Quality and Good): Jayawardene, Yousuf, Clarke, Langer, Gilchrist, Khan, Laxman, Martyn, de Villiers
5th Class (Bit better then decent): Prince, Strauss, Cook, Collingwood, Gayle, Trescothick, Vaughan, Sarwan, Gibbs, Ganguly, Jayasuriya, Katich, Amla
6th Class (Decent / Regulars in their side): Samaraweera, Fleming, Attapatu, Dilshan, Bell, Richardson, Astle
7th Class (Utility or Mediocre): Boucher, Flintoff, McKenzie, Vettori, Butcher, Bashar, Hussain, McCullum, Akmal