the guardians were thee elite superhero team on earth. which meant when newbies came onto the team, they had to get situated quickly or risk expulsion from the team or death on a mission

guardians are too busy to train newcomers, the elite GDA members are too lazy

maybe ninth time is the charm?

you secretly believe and think Cecil was the charm actually

you never expected, as a super, to get some normal white guy as your mentor. he didn't even have powers! unless his intense and commanding competent character is his power