Having been alongside Clarke at Stamford Bridge for three years as part of Jose Mourinho's backroom staff, Villas-Boas is glad to see his former colleague doing well.
"He is an excellent person," Villas-Boas said. "I have nothing bad to say about Steve.
"It is fantastic to see him doing well. It has been a great learning experience and a great opportunity at West Brom.
"We had a excellent relationship. I am not sure what captivates Steve is the same as captivates me."