Since it wasn't a deep wipe (I presume since it was factory reset), users could potentially recover data using tools like testdisk https://www.cgsecurity.org/wiki/TestDisk
That's assuming it does not issue ATA Secure Erase to the drive - whilst WD drives of the era were using absolutely atrocious controllers for the most part, it would be enough to thwart testdisk.
Also, while this can be done recovering data from a raid volume is a lot more difficult than just running testdisk, great as it is.