Read this: http://matrix-radar.com/2017/09/a-lesson-in-fmla-damages-fmla-retaliation-in-layoff-costs-verizon-big-money/
TLDR: if you were given a Developing rating in the last couple of years, and it was supposedly not due to FMLA, but in reality was, and you are RIFed then you may have a case.