Except for spermatogenesis, which requires a temperature lower than internal. Back to school for you, budding biologist.
I think he understands that.
He probably doesn’t see a reason that they would move all the way down there over the course of time. Why wasn’t the original point sufficient? It must have worked at it’s original point?
If the new point outside the main part of the body didn’t happen all at once, how many millions of years would it take for this accident to happen, and what possible benefit could there be during the journey, to make the accidental slight movement an advantage, and worthwhile?
I think you miss the irony.
How would an organism “know” that spermatogenesis was more effective using external cooling if every animal up to that time used the internal model?
Testicular migration is a pretty complex process and I haven’t seen a good argument for how you get from internal to external gonads.
The big problem is that many modifications are necessary to get the testicles into their new position in working order. It isn't just a single mutation. How all these different changes took place without compromising reproduction during the intermediate stages presents serious problems, esp. since we have no fossil record of the postulated intermediate stages. I'm not saying it didn't happen, but that the facile arguments of "pop" evolutionists skip over all the difficult details.