Speculation alert
Players get a good idea of where they will be drafted from WNBA sources. I wouldn't be surprised if DeShields found out that she was not going to be the No 1 pick and maybe not even No 2 and that it had an effect on her decision. While I see little difference between Davis and Deshields, Diamond has a history of chronic injury and perhaps WNBA teams weren't eager to pay her to sit.
And IMO Tenn will right in the middle of the race for the SEC title next year. In addition to getting Cooper back and assuming she is 100%, the obviously talented freshmen will enable Warlick to demand more effort. This year her depleted roster meant that she had little choice if a player or two gave less than their best in both practice and in games. This year she can sit them.
As for all the transfers, there are a lot of possible reasons talked about and given out by the players, the most common being "home sickness". Conspicuous in it's absence as a reason for their withdrawal is academic difficulty. Without being specific and without knowing the intricacies of the NCAA rules about maintaining academic eligibility it seems that there has been a spike of high profile players leaving programs and it started at the same time that the UNC situation hit the news. Again, it's just speculation but only a naive person would believe that UNC is the only school in the country that "arranged" classes for it's athletes. It may be that AD's all over the country, afraid of seeing their own programs being closely examined made it clear to their staff that there would be a zero tolerance of anyone involved with anything approaching what went on at UNC, and as a result any athletes in danger of losing their academic eligibility were faced with withdrawing from their school and finding another as opposed to having a phone call placed to their instructors.