If you were travelling from A-B, and planning the journey yourself, you might look it up on Google Maps. GM would give you a route, and an estimated time for the journey - let's say it's one hour for our mythical trip. Now let's assume that the destination for our journey is the airport, as we have a plane to catch - i.e. we absolutely have to be there on time.
In this scenario, would you leave the house one hour before the flight departs (let's ignore the reality of parking / check-in / security etc. - we're on the company jet, just driving up to the plane)? Of course not - if you had to be there on time, and you were taking someone else's directions, even someone with the 'authority' of Google, you'd probably add at least 50%, and probably 100% to the estimate. Even then, you're still subject to the vagaries of the traffic - something that affects everyone, regardless of whether they've driven the route before.
If you were to approach the journey from an agile point of view, you wouldn't book the airline ticket in advance - you'd catch the plane when you got there. And you wouldn't plan the route either - you'd hire a driver, who knew the route, and simply tell him the destination. He'd make up the route as he went along, avoiding traffic problems if possible by using his previous experience. It’s pretty clear that if you just set out from A, travelling to B as fast as you could, it would take less time than if mentally started at B, then worked backwards to determine when you ought to leave A.
Agile behaviour in a software development team requires a similar faith in the ‘driver’ – in this case the people in the team. The quickest way to reach your destination is to have faith in the team to deliver, and to make sure that they understand the destination. If you then insist on them following a specific route, then you have just removed their capacity to avoid delays and dead-ends – removing the reason you hired them in the first place.
If you want to be agile, you have to trust in your team.
(And yes, this does mean that outsourcing a project cannot be agile. It also means that agile is NOT a project management methodology. It’s a way of working.)