We're talking about 144hz at 1080p.
Low Res = CPU bottleneck, Higher Res = GPU bottleneck. the whole point of testing games at low res is to take the GPU out of the equation, see how much the CPU bottlenecks performance, higher res just offloads more work to the GPU and it becomes the bottleneck.
Looking at that chart a 9900K will gain him about 15%, a good amount but not enough for the price diffrence, which is presumably why he owns a 2700X not a 9900K and is hoping Ryzen 3000 is faster than the 9900K, i think that's unlikely but certainly it should get him the same performance as a 9900K.
We are expecting about a 15% performance boost over Ryzen 2000.