An entity like the VA is probably so screwed up, with a deeply entrenched organizational culture, that one person in a few years can't make a dent.
During my corporate career, I learned a bit about organizational cultures. They fight back over change. Even versus a top leader.
Watching the difficulty Trump and Sessions seem to be having with the DOJ-FBI is one example.
All of that goes for State Dept., too. In Reagan's time top GOP operatives (Kitchen Cabinet) from Calif. made the point he had a couple of thousand political appointments.
I'm fairly certain those people would admit they fell short of reaching all of their goals and objectives. Remember in those days Cold War was the big deal. Number One.
But I also think they would say they did their best, hoping others would continue. Twelve years of bushes is all we got, until Trump.