When a new build emerges, it's easy to get an estimate for its minimum power level, and an idea of how far it can go, but until the absolute best combination is found and the most optimum playstyle is worked out, we likely won't see its maximum potential until later. In the past, we had longer testing periods, and thus more time was spent finding the 'perfect' version of a new build before the PTR ended. We currently have rather short testing periods.

So I can guarantee they perform at at least top A-tier levels, and I assume they can go further because not as much testing went into these builds vs the new builds. But I don't know how much further above 150 they can go, so all I can base myself on is seeing some clears on PTR in the low-to-mid 140s for these builds. If they could theoretically do a GR 156, then a 10 GR nerf would bring them down to GR 146.

So let's say they are hit with a nerf of 10 GR levels - does that bring them down to GR 140? Only if their max potential was GR 150.

Mundunugu and Valor were clearing GR 150. It's not just you - good observation! So, a couple of reasons:

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