Originally Posted by Trakhak

As shown in the photo, the derailleur was scraped along the ground in a previous crash; the impact bent the derailleur inward toward the spokes.

Having heard the "It wasn't my fault" defense plenty of times in my bike shop days, that's the first thing I always looked for in cases like this one. Open-and-shut case.

In the future, always check the rear derailleur and dropout for damage (or take the bike to a shop to be checked) when you crash a bike on its right side.