The Ripple Effect
If you will, think of it like so:
Doctrinal enforcer perceived as "hammer of heresy" is elected Pope.
In first major move, Pope proves perception unfounded by naming reserved, pragmatic compromise-builder to succeed him as doctrinal enforcer.
To settle business at home, consensus-seeking doctrinal enforcer champions appointment of beloved, pragmatic, urbane compromise-builder to take his place.
Beloved, pragmatic, urbane compromise-builder takes possession of the province which includes his former see. As metropolitan, said prelate has significant input on the choice of his successor in the former see. And so, reinforced on the other side by pragmatic, compromise-builder doctrinal enforcer who enjoys the papal confidence (and will, barring the unforeseen, serve as relatore when the case reaches the Congregation for Bishops), beloved, pragmatic, urbane compromise-builder metropolitan sends to Rome a recommendation that he be succeeded by one like himself, one he knows, respects and trusts.
Moral of this exercise: The mold is set. It's not a question of what. It's a question of who.