Those that sound like they know what they are doing, seem to make good decisions, appear to the manager as someone that will make them look good, and seem to be

Those that sound like they know what they are doing, seem to make good decisions, appear to the manager as someone that will make them look good, and seem to be someone the manager can understand and trust will be promoted over someone with more domain knowledge and technical ability that doesn't have those other qualifications in some cases. Don't assume a meritocracy, even if it had seemed that way initially, because managers change, and things often don't work like that.