Revisiting 1963 Topps Mantle Potential Color Variant

[packs]

I purchased my SGC 2.5 years ago and asked initially whether anyone felt like the blue box on the bottom of the card, which is supposed to be green, was a variation of the card.

Nearly everyone said it was the result of natural fading due to some kind of exposure.

I moved on. Then I found a second example in another auction a year or two later. Now, I've found a third.

Here are all three examples of the blue box that I have found since I bought my own. They all have the same look to them. While I was originally happy to accept that a fade was a fade, I find it harder to accept that the same fading occurred in the same way three different times. There is almost no variation between the cards, but you'd think there would be if it was the result of natural fading under various different circumstance.

Is it still everyone's opinion that these cards are simply faded?