DDN archetecture helps
If the DDN architecture holds to their previous kit, the Fibre Channel connected raid controllers have 10 FC loops out the backside. DDN's secret sauce has been the ability to strip data across those 10 loops in parallel. A parallel connection system of SSDs could be how they are out performing NVMe device sub-systems.
NVMe isn't magical, it still has limits. It appears DDN is just being agile in leveraging their architectural strengths.