Unfortunately for Claire Williams, the slump started when she took over.
Claire Williams was appointed deputy principal in early 2013. For the five years previously, Williams had finished 8th, 7th, 5th, 9th and 8th in the constructor's championship. While they finished 9th in 2013, they finished 3rd in 2014 and 2015 after her appointment, their best results for over 10 years, and 5th in 2016 and 2017. I don't think the data supports your assertion.
Claire Williams was appointed deputy principal in early 2013. For the five years previously, Williams had finished 8th, 7th, 5th, 9th and 8th in the constructor's championship. While they finished 9th in 2013, they finished 3rd in 2014 and 2015 after her appointment, their best results for over 10 years, and 5th in 2016 and 2017. I don't think the data supports your assertion.