From United's page on earning miles, it seems that for most United flights, miles are awarded based on the fare rather than on the distance. As far as I've noticed, the miles I get from calculation based on the fare is substantially less than if the calculation is based on the distance -- approximately only half as much.
Is this a recent change that I've missed? The reason I'm asking is that I'm earning much fewer miles now than the same flight last year with the same fare class.