Although I'm skeptical (though see below), as the sibling comment is, that this small an increase in best case latency would make a difference in a typical office environment, I'm curious if it was (as close to) apples-to-apples as possible. That is, was it comparing 802.11ac to gigabit ethernet (or 54/108 Mb/s Wifi to 100Mb ethernet), and were the interfaces connected the same way (e.g. both via USB or both via PCIe/Thunderbolt)?

Despite my skepticism, I've seen that, in the typical office setting, wireless latencies can vary much higher. It stands to reason that, no matter how well-engineered, it's still a shared medium, which means that congestion or interference caused by a neighbor can ruin someone's VoiP call during the time it's happening.