Compare the corpus spongiosum in the normal penis to the damaged hard flaccid penises. In the damaged hard flaccid penises the corpus spongiosum gets noticably thinner wheras with the normal penis it stays the same width.
Source: https://www.reddit.com/r/Hard_Flaccid/comments/ua8n4s/could_abdominal_fascia_latched_onto_the_bucks/ Reddit, April 2022