The person I'd replaced had left for another agency five months before I arrived, and there was little information left behind for me to build on. Right from the start, there was a lot of catching up to do, and little time for learning the details. The very same thing happened to the person who replaced me in the agency I'd left. When you lose an IT worker, the bulk of that accumulated knowledge goes out the door with them. Right now, we've got a revolving door, and it's well oiled.
Every revolution results in a net loss.
The loss of knowledge, or human capital, also occurs when consultants are used to cover the shortage of State IT workers. When the contract is over, the developers move on and large chunks of corporate knowledge walk out the door. This hurts all agencies, but the smallest hurt the most. Losing one IT worker can be a serious setback. These small shops must have the means to advance their existing IT workers in order to preserve their knowledge assets.