The Army is not full of pilots. Due to a number of reasons, the Army has a major backlog of people waiting for an operational conversion. Since the training system can't produce pilots any faster and is already running at capacity in terms of output, its only option is to slow its intake of fresh trainees to allow the backlog to clear. This will take a long (!) time. Even if it magically trained everyone waiting overnight though, the regiments would still be undermanned.