Mind boggling. When I was young (in the 60s), every white catholic basketball player crossed himself at the line before shoooting a foul shot. The late, great, Al McGuire caused the tradition to go away in an incredibly short period of time, when he told one of his players that "I just heard from God and he asked me to tell you to stop doing it. He says you make him look bad every time you miss." And yet, here we are.
The Establishment Clause, while sometimes tricky at the margins, is just not that difficult here. Every player, every coach, is free to practice or not practice their religion as they see fit, but an arm of the government (including the UConn football team), and those who work for it in their capacities as employees, can't use the State to support any particular religion or religion as a whole.
So players can do what they want as individuals, and do (see prayer huddles after games), but a coach of a state university can't make prayer or Jesus part of the team or its routine.