Saw a clip of Plummer playing for Denso's first match against Hisamitsu and the girl couldn't keep up. The pace is a lot faster than what she's used to, I guess. And as someone pointed out in the V.League thread, she was struggling to jump. Denso better do more rounds with her to let her get used to their style.
Not surprising. Being in Japan will be good for the USA fast. She was struggling in the exhibitions they played against Canada.