I think all of BG was possible in the current LFR gear when each rank was released. But really hard in some cases, depending on your class. I personally couldn't beat Big Badda Boom until SoO came out and I got my cloak (I'm a Rogue... maybe I just suck at target swapping though).
When I say LFR gear, of course I mean VP gear ie NM-equivalent ILVL :P
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All true, but also Blizzard has mentioned that ILVL gaps increase as time goes on because more of a differential is needed to make DPS seem like a big improvement when the base numbers are high.