I agree just watch Kerber's interview after her last match and you will realize that she got lucky to escape in that match with a win. She seems not convincing to me. Her play and demeanor doesn't convince me to be honest, the only positive in this match that really favors Kerber in this match is that she get odds above 2.00 as the underdog.
Let's say this is a 50:50 game then you could go with the underdog Kerber for value but I honestly can't see value on Kerber, she not a true #1 from my point of view.
I maybe consider this game to go under in total games (21.5 games) as a lean since I can see Muguruza taking this in straight set, but it's a borderline pick because grass suits Kerber.