Even so, I'm surprised it's able to match a 9900K in any scenario!
The 3300X is also different to the rest of the Zen 2 CPU's, it only has one CCX. With more than one CCX Zen 2 very often has intercore latency as core to core communication happens outside of the CCX, compared to Intel Ring Bus on mainstream CPU's that has an impact on gaming IPC, that's an up side for Intel but the down side is the ring bus architecture doesn't work above 10 cores, all the Skylake-X CPU are a "mesh" architecture and they suffer from the same intercore latency as Zen 2 with reduced gaming performance.
There are rare occasions where the game is only using 1 or 2 cores and with that intercore communication doesn't need to happen outside of a single CCX and the gaming IPC is like its productivity IPC, very good.
The 3300X with its single CCX behaves more like the Ring Bus on Coffeelake and with that has higher Gaming IPC than the otherwise identical 3100 which is like all other Zen 2 CPU's; dual CCX.
This is a 7% difference in IPC.
The image below that, CS:GO, ironically an old DX9 game only uses a couple of cores and with that only uses the one CCX inside the 3900X and again the gaming IPC is very high.