Either of the two reasons given by Hua Liu would be sufficient for Dai Li to be made the group leader.
As for these three, being recruited by the national team was impossible. They hadn't didn't qualified for the national training camp, while Dai Li could gain a firm foothold in the national team. This showed that he was much stronger than them, and thus could be eligible to be group leader.
Besides, Dai Li was Li Xue's favorite disciple, who was the second in command on the national track and field team. Xue was very influential throughout the whole country due to his numerous disciples and longtime followers. Relying on his relationship with Li Xue, Dai Li could make himself the group leader.
Considering this, Baojun Sha suddenly felt a sense of loss. He had trained for quite a long time to be the group leader. Now, the chance was taken by someone else before he could even get his hopes up.