i don’t know if i am qualified to answer this, but here is my research and experience.
when it comes to smaller diocese (what’s the plural of that?), the metropolitan supplies the vatican with candidates. he consults other local bishops, but the list is essentailly his. the vatican picks from that list or finds another choice. i don’t know if the nuncio is involved. in some cases, i would think that at least a papal legate would have to help. the pope can’t meet everyone personally. it seems to be generally recognized that it would be uncommon for the vatican to pick someone off the list, and ‘import’ someone into the local Church. also, there is no way of knowing if the new bishop really personally knows the pope. one of my parish priests from when i was a kid became a bishop. i don’t think he knew JPII, but he could have. the pope makes the appoint though.
when it comes to an appointment of an archbishop, it gets more serious. he is the metropolitan of his area. there is more scrutiny. they are usually chosen from men who are already bishops. still, they don’t have to be. in some places, it is even more scrutinized.
there are diocese that traditionally have cardinals as archbishops. so when the archbishop is appointed there, they keep an eye on that. there are political aspects to the decision. take mahony as an example, or even mccarrick. when mahony became archbishop, at least two of his predecessors were cardinals. it is the most populous diocese in the u.s. if he were never elevated to cardinal, what would the Church be saying about him as an archbishop? ultimately, failing to make him a cardinal would detract from his office as pastor. when they put him in, they knew he would be a cardinal. they didn’t make that decision lightly. once he was archbishop of l.a., was guaranteed the office, even if his action and attitudes subsequently disappointed or surprized them. the same with mccarrick and law.
the pope personally knows, or at least has had dealings with, those he elevates to cardinal. good thing that there are lots of cardinals to balance out the mix.
the thing to keep in mind is that there are plenty of cardinals who are elevated by merit alone. it is a “good ol’ boys” network and the standard is holiness. ‘imported’ bishops and those made cardinal at a young age are people to pay attention to, IMO. they haven’t broken the mold for no reason.
lastly, just so you and i keep our feet on the ground, let’s consider the media propaganda. “conservative” is what we want in our shepherds. it translates into ‘faithful’, for those of us who worry about following Christ and not men. painful and confusing as it may be, i will follow a “conservative” to the death. the minute that i sense self-denial, i sense Christ. i am proud to know that i am doing wrong, as opposed to someone telling that what i am doing is not a sin. i may not repent before i die, but i have no hope of salvation, if someone leads me to wallow in my sins so that i cannot even see the evil. i have done a lot to offend God, but thank God that no one ever convinced me that it was ok. so don’t only pray that the college is “stacked” with conservatives, but pray that we will all shed our own blood to become one too.
