The most important problem faced by the ULF team, even before they go underwater, is their incompatibility. Although the team had been proposed and tested by Norman Johnson back in the 70s, they are not friends and do not get along well together. Almost from the first, personality issues occur:
"You wait," Adams said. "A week from now, this is going to be recognized as one big fat false alarm. Nothing more."
You hope, Norman thought. And again wondered why.
(Crichton, Sphere, Google Books)
As the book continues on, it becomes clear that these people are not meant to share working space. Their personalities clash and eventually become the driving force behind the attacks and destruction of the underwater station. Since very little time was taken to assess their mental states, and even less to see how they interacted together, their failure to work as a team could only be predicted by assumption, not by science. Throughout the novel, opposing views create an atmosphere of suspicion and impede their ability to deal with crises as they occur.