The conclusion will be that she has come to thrive from a "2nd place" position.
The argument is that as others took the spotlight (e.g. Risako) Chinami's personality had more of a chance to develop esoterically; that is to say amongst the other Berryz and in private.
An example of this could be that boyband romance rumour if that has some truth or her dancing in the Genghis Khan PV (which definitely seems to show "personality") or even just her expression in some photos e.g.:
...There's more than meets the eye!
* http://www.answers.com/topic/drafting-racing :
Drafting or slipstreaming is a technique in sports racing where competitors align in a close group in order to reduce the overall effect of drag or fluid resistance of the group in a slipstream [...] Drafting can be cooperative, in which several competitors take turns in the lead position (which requires the most effort and energy consumption). Or, it can be competitive or tactical, where one competitor will try to stay closely behind another leaving him or her more energy for a break-away push to the finish line.