No point changing the captain when the strategy from the top is failing.
And that goes beyond test cricket. You need to have the right structure and foundation for your test players to excel. Right now, and for a fairly significant amount of time, that isn't there.
There's only so long you can dine out on strong home performances or iconic players thrashing out quality innings (Root and Stokes, maybe Brook).
Gotta be wholesale changes beyond just the playing squad.