Have to agree with KomdotKom - its knackered, I'd give you 10quid for it and assuming your in the UK I'll even pay postage.
Grains look lovely on it - its had a refurb by the looks of it too me but unless you paid 400 for it and you never intend on buying another bat ever again then just use it and enjoy it. if the corner starts rolling over again just glue and clamp it.
If the yellowing you are referring too is the darker section towards the toe surely thats just as a result of the bat being oiled when stickers were on it and then refurbed without them... in my experience of a rerun the wood under stickers of a previously oiled bat always has a slightly lighter look about it - unless you take alot of wood off the oiled areas when sanding.