It’s subjective but it’s all in fun. This isn’t supposed to be some sort of metric like used by NWS but most people all have the same underlying principles with some variety. Some weigh in snowpack retention, some with how long the season actually lasts (for instance Nov-Mar), and some like myself perhaps weigh in the snowfalls along with retention.
With two large events it’s hard to argue against a very good grade for me. This area is any exactly retention central, but this year was excellent for that so I would factor that in. However December left a little to be desired given how good the pattern was for cold, and if March is a dud that doesn’t exactly bolster the grade either.