Different situation ..... Mountcastle hit .312/.344/.527 in 544 at bats in 2019 at AAA. He was clearly ready and I'm not sure how you think the Bowie time impacted that. He started at the Bowie camp only because there was no AAA. He started at the Bowie camp to delay the clock.
I think because of the way that 2020 went, level/placement will be more of a combination of scouting and performance than just performance. For Rutschman, that means that while you can justify starting him at lower levels, you also likely have enough to go on to start him in Baltimore on opening day if you really wanted. That argues for a AA assignment, though A+ wouldn't shock me I guess.
On Diaz, I personally believe that he has already shown he's ready for AAA. So, for me, that means I'd assign him to AAA. From there, he has issues that he needs to work on, most notably his availability and production over time. He has flashed nicely at times, but then he inevitably has missed time for various reasons and tends to start slow upon return. That seems to have suppressed his stats. Also, I honestly think there's a red flag in there somewhere with Diaz. I think the O's like the talent more than the make up. If he's traded, I wouldn't be shocked at all. I also acknowledge that I'm reading between the lines here and have no strong evidence, for what it's worth.
You are right..it’s not the answer I’m looking for because it’s not an answer to the question you were asked.
If I ask you, what is your favorite color and you tell me a banana, that is an answer and it’s not one I’m looking for..that doesn’t mean in insulting you, it just means that trying to discuss this with you when you clearly don’t want to answer the questions and you want your agenda is a waste of time.