Both proficiency and growth are important.
In kindergarteners, growth is far more valuable than any proficiency. On college graduation day the potential for growth should be intact, but it’s more important that the graduate has some finished skills.
At a professional level, the growth achieved must be on top of current proficiency. In educators, in orchestra musicians, in surgeons: growth is important but only because they are already proficient.
Surely that is true for Cabinet Secretaries, too.