I mean, the numbers won't resist, and you could just subtract 1 from each score to anchor it to zero, although it is best to just make the range of possible values clear. It is much more questionable whether the arithmetic mean here provides a valuable interpretation, as it assumes that 'Good' is 3 times better than 'Poor', etc. In the end, the assignment of numbers to the verbal anchors is purely arbitrary.

Best,

Josh