I imagine this is where the reputation of a good manager comes in and the ability to say to their boss "hey, we should keep this guy... just trust me on this."
If the company runs on reputation it’s only a matter of time until a consultant comes in and processes are established to move to a more efficient metric based management style.
Yeah, it's tough either way. Some managers might be biased and keep praising some of their reports that don't actually provide good value for the company. For an outside observer that has no intimate knowledge to the work, how could this be differentiated from the manager having a backbone to support a report that does truly great work but there is no good metric to prove it?