2010 D Quarter Grease Filled Die, Worn Die, Or Something Else?

How to tell the differences between the suggestions? Well when determining which it is, you need to know how each suggestion would affect a coin.
First off, determine how the devices are affected? On your coin the devices look weak. But look closer at the affected devices:
1. Note the height of the devices?
2. Note the width of the devices?
On your coin they are weak, thin is height, and wider than normal. What causes this? A partial fill with grease is the issue.

Note the different angles of the grease on some of the images? These are caused when a die is wiped down and forces the grease in a direction with a cloth pushing grease in a direction (angled in the dies devices) Thus that is not what happened to your coin. But as the coin strike more and more strike the grease can bottom out and affect across the devices, like on your coin. They are even, not angled. So the grease is filling those devices in a level pattern. So when you see the devices looking wider, the taper is filled at the top of the die, only allowing the wider areas to be see on the coins. Thus there was a grease issue that caused the problem. That is how you determine the issue that caused the problem with the strike. I know I'm giving a lot of details, but I want you to see, what I see on your coin. And how I came to my conclussion. (It's like I was there by your side)

CoopHome: How can I tell if there was a Struck Through Grease issue with my coin? What should I look for on these?

Great description and graphics as always Coop!