I suppose Chris Grayling can't be personally blamed for all the poor decisions of the DfT» under his charge. He's signing off on poorly thought out plans, I doubt he's thinking them all up himself. I suspect he doesn't have the nous or creativity.
It's more like a lunatic running the asylum.
Yes he can. The minister should have the big ideas, with the Civil Service turning them into reality. Things only start to go wrong on the railways when something changes, and Patrick McLoughlin didn't have the same issues in the 4 years he was transport secretary, and he had a lot more on his plate.
When the cock-up fairy visits a department once, it can be easily mended most times. When she seems to have set up an office within the department, the minister's choice is normally between tendering resignation or keeping the desk fairly clear to make it easier to move out when sacked. He has made some rather expensive errors of judgment. Others have been defenestrated for less.