RAID total throughput vs lun throughput

I am analyzing some nar files and noticed that RAID group performance is not a sum of performance of its luns (Flare, not meta). for example I saw a RG whose total throughput spikes at various times. I compared it to the lun total throughput and while I do see spikes in the lun, those spikes are not so big as to explain the RG total throughput. Is there something else going on in the RG that explains the spikes and performance?

I am attaching a screenshot of an Excel graph created from the nar file data. Blue is the RG total throughput, and the red is the lun throughput. There is only one lun in this RG.