BVBs business model for the time being seems to be: be a top talent developer with the goal of selling the prospects on to generate cash, and hope to reach a CL rank in the BuLi, forget about silverware. Then they sacked a coach who is brilliant at developing players, apparently because he lacked the personality/charisma deemed necessary to win silverware. Doesn't make much sense to me.
That's basically the lazy cliche that people keep repeating. The reality is that the club buys a lot of mid to late 20s players (e.g. Can, Schulz, Hazard and Delaney) as well as some proper experienced players such as Hummels and Witsel. Given these investments it's only natural to expect to stay clear of Leverkusen, Gladbach or Leipzig and try to grab something more, if the opportunity presents itself.
Favre was supposed to see out his third year, it's not exactly rash management to think about changes after such a time span. The actual sacking happened, because things spiraled out of control short term. And as far as being brilliant at developing players goes: some players prospered under Favre, others didn't. Same as with every coach. Outside of the PL basically every "good" coach is "great" at youth development, Rose (as the likely replacement) is no exception to that.