Could have gone either way but if I had to guess, I'd say Dottie intentionally dropped the ball. She was just too good to fumble something that big and it was clear she never cared that much about the game anyway. She also knew Kit wanted it more so she decided to let her have the glory at the end.

Yeah Dottie only did it for her sister and after the revelation that she was always perfect I think that made her throw the game. It was that or her sister. The choice was easy.

It could be either interpretation, depending on your assessment of Dottie. I don't think Dottie dropped the ball on purpose. If she had, then Kit's achievement would have been hollow. The game might not have mattered to her, but Dottie is way too competitive to have dropped the ball on purpose during the most crucial play of the game. The only way Kit was going to help her team win was to earn it by bulldozing over Dottie. And I think she did.