And there is more: if you remember the Apollo 14 episode from "From the Earth to the Moon", Mitchell made some rapid calculation in order for the radar to start working again while on powered descent (they had until then no clue about their altitude): Mitchell saved the day and Shepard listened to him.
Also, Mitchell advised Shepard to take a direction that would have led them right to Cone Crater, Shepard had another idea, Mitchell followed the boss and they never reached the rim of Cone Crater.
And when we know that Apollo 14 became famous for Shepard's golf play and not for the science (many of the rocks collected were wrongly documented and turned out to be not scientifically significant). Clearly, Shepard's ego was not in sync with the scientists and much more in sync with Slayton (who could use Shepard's return back to flight status after an illness to return himself back to flight status and fly on the ASTP mission).

Raoul (those Mercury 7 astronauts were definitely not as good as the following 9 selected)