Okay - here's the deal: The chain looked like it was too long as soon as I flipped your first picture right-side up so I didn't get dizzy. Then your next photo shows the chain - large to large - and the RD. The RD is standing nearly at 6:00 - 12:00. And this confirms that it's in need of losing a link. It should be more like - large to large 3:30-4:00 - 10:00.

If you can pull the wheel far enough back to find these dimensions - wow! And you must have very looooong dropouts! But go ahead and try. Then post another picture if you would.

I'll be adding a photo with one of my bikes in the large-to-large configuration, so check back in a few...

Oh - and this has nothing to do with chain-wear.

<EDIT> Here we go.....