It is something I've noticed while watching the Baylor games. It seemed to me that Griner was slow in transition, but I wasn't sure if it was just that her long legs made it appear that she was moving slowly. So, I took a stopwatch and timed how long it took her to get to the other end of the court on a variety of plays. I did the same for Dolson. I noted that Griner was often 1 to 3 seconds slower on a majority of plays. I also noticed that Uconn on defense in general plays a step closer to her man and thus expends significantly more energy guarding. Also, Uconn full court presses much more than any of the teams you mentioned. Also, Uconn is much more active on offense. All of these thngs lead me to believe Uconn's conditioning is superior.
I contend that Griner purposely trails on offense. I believe it to be part of the offensive scheme to have her moving to the basket so that she is not just standing under the basket to allow for three defenders to surround her too quickly. Not setting up too early and getting pushed on as quickly does allow her to save some energy as well. I have seen her draw a lot of fouls from defenders who are trying to prevent her from moving toward the lane.
I could be wrong, but there has even been discussion between Mulkey and Griner about her trailing. Griner is trying to talk Mulkey into letting her shoot the three as the trailer as well...don't see that happening too often. For anyone who goes to the game, keep an eye on Griner shooting threes in warmups. It is quite impressive and one day will be a weapon that Baylor uses.
On defense, BG does not have to lean on defenders. She can play off of them and still block shots, thus conserving her energy. Griner doesn't have to use nearly as much energy guarding as her opponents do. Dolson will have to exert a lot of energy guarding Griner and that will have an impact on her tendency to pick up fouls and also will affect her on the offensive end since it will deplete her energy level.