In this category you are not pricing an object. You are pricing an object and a claim, and the claim is the part that moves the number most.
What moves the number
Worn, issued or replica. The largest single price difference here, and the one most often got wrong.
Who and when — the player and the match.
What you can show — a photograph of the signing, a certificate with a named issuer, a chain of ownership.
Condition, said separately from all of the above.
Why two of the same differ
One shirt comes with a photograph of the moment it was signed. The other comes with a sentence. The provenance ladder sets out the five rungs; where you are on it is most of the price.
How to find out rather than guess
Compare completed sales with the same level of proof. A documented match-worn shirt and an unverified one are not comparables, and averaging them produces a number that belongs to neither.
Then be honest about which you have. "Unverified, sold as seen" prices lower and sells cleanly.
A certificate is worth its issuer
Not more. Look up who issued it before you let it carry any weight in your number.
Questions people ask
Does a stain lower the value of a match-worn shirt?
Often it raises it, because it is evidence of use. Describe it rather than apologising.
Is a signed item from a public event worth more?
Yes, when you can say where and when, and more again with a photograph.
Can Metzee tell me if a signature is real?
No. Metzee handles the money, the delivery and disputes about description. What Metzee will not do.
More: pricing memorabilia, provenance.