Exactly. I think there's a lot of endowment effect going on here.
People seem to forget that while Henderson is younger, he has quite the injury history. His value has to be discounted for that. If you want, substitute Brandon Sproat who is about to turn 26. But Henderson and Sproat are the closest to River Ryan in terms of stuff and major league readiness whether people like it or not. And River Ryan made the majors at age 25 despite being drafted at age 22, then he got hurt. It's not like it took him until age 28 to knock on the major league door.
Pena is still in high-A. He hasn't proven that he can make the jump to AA yet, and he has some health concerns as well. Those have to discount his value. Meanwhile, Hope has a .899 OPS in AA.
Pull out any A-ball SP comp you want. Smith is averaging 13.7 K/9 to only 3.6 BB/9 this year, mostly at low-A. I'm struggling to find a Brewers SP prospect who at 21 years old averaged >11 K/9 and less than 4 BB/9 in any meaningful sample of innings. Smith was a 3rd round pick who got $700K.
It's a much better comp than people think.