Gotta disagree with the OP. UCONN players do NOT endure extreme mental and physical hardships. That sort of makes it sound like players are tortured. I'm sure that's not what the OP meant (at least I hope not), but as
@eebmg said, Geno and CD.
They prepare the players better than any other team in WCBB. Practices are harder than games. Geno sets them up to fail in practice - going 4 on 5 for example. They are incredibly physically fit - at least as fit as any other team out there.
Plus Geno recruits not only really talented players (ie. highly rated), but kids who WANT to play team ball, who are great character people, who are highly competitive and motivated, and who are coachable. The term is often used regarding the freshmen that they need to be "broken down and then built back up". I don't care for that term but it's not far from the truth.
Many coaches take a talented freshman and work to enhance what they already do really well. But they pay little to no attention to the things they struggle with. Geno and CD do 2 things - break the bad habits and teach proper habits (Megan Walker perfect example - took her 2 years to REALLY get it), and push them to do more than they ever thought they could.
I do agree that he's a master of taking individuals and getting them to perform at their max potential as a team. I also want to add something about recruiting - potential recruits meet the team. If the team feels it's not a match, the recruit won't ever be part of UCONN. Good chemistry is essential. The coaches sometimes get it wrong. Kids who don't fit in end up leaving. Others leave for lack of PT. But bottom line, 99% of the time, the team has amazing chemistry and that's pretty amazing when you consider the top talent they recruit who could be prima donnas...