Welsh Secretary Peter Hain told the Welsh Affairs Committee there had been shortcomings in the transferring of powers from London to Wales since devolution.
Mr Hain said the first legislative competence orders (LCOs) - the system by which Welsh laws are made - had been rushed out.
He said things had started in a "bad place", but that the situation was measurably better now than in 2007.
The committee said there was concern over a lack of understanding of devolution among London-based civil servants, and suggested that the Wales Office lacked clout.
"The Wales Office is a midget in Whitehall terms, but it is a feisty and powerful midget in terms of batting for Wales," Mr Hain said.
He added that around a third of staff were seconded from the Welsh Assembly Government.
"They are not going to short change Wales."
Asked whether there was a lack of communication between civil servants in Wales and Whitehall, Mr Hain said: "There are shortcomings on all sides but the great tide of devolution is flowing strongly and very well."