The article incorrectly states that low leakage (high binned) chips are easier to overclock, but if you talk to actual overclockers, they all pretty much agree that leaky chips overclock better because the transistors parasitic components are less effective at undermining the transistors switching speed.
This is why in GPU ASIC Quality, a higher ASIC quality (which has less leakage and lower power per clock) die has less overclock headroom because a higher ASIC quality means higher quality transistor means higher quality transistor parasitic properties which means more difficulty clocking higher.
This is why in GPU ASIC Quality, a higher ASIC quality (which has less leakage and lower power per clock) die has less overclock headroom because a higher ASIC quality means higher quality transistor means higher quality transistor parasitic properties which means more difficulty clocking higher.