I think Trott's current travails shows what difference baseline ability makes to players when they're not in prime touch.
I reckon anyone who's watched any reasonable amount of cricket would say, after watching the two players in action, that Pietersen was the more lavishly gifted batsman and even when he can't buy a run he always looks likely to score if he clicks (SLA excepted, obvz), but Trott, with his more limited, pared-down scoring options, can look nigh on shotless when he's not quite there.
Had similar spell during the 09/10 SA tour and he managed to get out of that, thanks in part to some friendlier offerings on the following tour of Bangladesh.
We're in NZ next, aren't we?