This may be Pova's problem - she can beat everyone else with her current game, but to beat Williams she has to change/improve her game radically. And that requires a lot of hard work and risk as well. But regardless of the technical points, I still think that the reference to "Serena's build" is a bit of a jibe, maybe it's a ploy to get into Williams head a little bit. It comes across as lacking thought at best and insulting at worst. It continues the long legacy of dumb/arrogant Pova quotes.