IIRC, Syleste started as a reporter at 12 News. Later, she co-anchored 12 News Weekend Today with Joe Dana. Finally, she was moved to the weekday morning news as a "sub-anchor" (at the time Fay was the main anchor, while Syleste and Joe Dana were secondary anchors).
Then, all of a sudden, Syleste was leaving and going to Fox 10. I'm assuming that 12 didn't renew her contract (but perhaps 10 made her a better offer). Given 12's anemic morning news ratings, I don't blame Syleste for moving to a much more popular show. During her time at 12, I just didn't like Syleste's news reading style (she and Joe reminded me of teenagers at the news desk). Perhaps she has now matured/improved and is on a show with the proper format to showcase her talents.
Certainly, news anchors can and do improve and mature over they years. When I was in college in the 80's, there was a reporter who was just starting out in Providence. She was very difficult to listen to, but continued to improve over time, and eventually became an anchor there. She then moved to Seattle and has been a reporter and anchor there for over 20 years.