They're experiencing a huge increase in their pilot requirements at the moment and they really are short. This current drive is to make up for the current shortage, as well as provide for even further growth. This was part of an agreement BALPA struck with easyJet to settle a dispute with crew over fatigue in 2016, a promise to hire more pilots and relieve the roster pressure somewhat, literally a few weeks later easyJet then announced the "generation easyJet" programme.