2007 Upper Deck Sweet Spot Baseball Forum

I have a number of these in the set, but this is the only one i cant quite figure out.  This aligns with what should be the blue ink variation numbering, but its clearly green ink.  Has anyone else seen green variations on the bat ?

I haven't found any checklist for green ink w/ the bat barrel. I did find a card for sale, stating it was the blue ink variation, but had the same coloring as yours. Perhaps the ink faded?

With sets like this I also often wonder how common it is for the athlete to mess up pen colors because I feel like that happens quite a bit 

I know the earlier sweet spot sets with the leather baseball autographs fade and discolor over time. The black turns in brown. That is usually what happens when it is in the light to long on display. 
mid it possible the wood soaked ink up ya it could have therefore it changed the color.  I don't know for a fact it does but this could be one reason. 
I have all my autographs in a wooden box to keep the light off of them so mine that I have pulled still has the vibrant colors. 

Blue fades to blue, but a different blue such as Turqiouse will fade to green.

I'd have to agree with T206, fading and absorption.  Different pigments (colors) fade and are absorbed at different rates depending on the material they're on.

At first i thought fading as well, but after looking at the correct blue, i can not see the pigment changing that much due to the wood and fading.

https://www.tradingcarddb.com/ViewCard.cfm/sid/23224/cid/2735192/2007-Upper-Deck-Sweet-Spot---Signatures-Bat-Barrel-Blue-Ink-SS-RH-Rich-Hill

I know there is a green ink 1/1 variation and wonder if its a used wrong marker issue, which wouldnt be the first time.

The Upper Deck website's checklists does not list a green ink bat barrel set.  They do list your card as a Tier 2 blue ink bat barrel.

http://sports.upperdeck.com/collectorszone/collectionprint.aspx?q=5&sid=46745