I'm kind of with everyone here: what legacy? He's coached one already fairly successful player to greater success, and it's still unclear he played any role in that success other than being a warm body in the coaching chair during the brief period of motivation.
The way he handled ditching Puig, though, has definitely made it so I, personally, would have trouble trusting him as a long-term coach. To do something like that without a conversation days before a major is just so chicken shit. I'd probably require an absolutely iron-clad contract spelling out the consequences of him pulling that kind of move in exacting detail.
Of course, given the vagueness around what the terms of his contract with Puig were to begin with, it's possible he'll be somewhat redeemed, but I don't see a way.
1. What legacy?
2. I would not over-react just yet. Sloane was in dire form this summer and basically had too little time to get herself back in physical and mental shape on such short notice. If this match was played like couple weeks later, I think chances are the result could have been different. Anna was very impressive, though.
With Sloane being historically disinterested in Asian swing, I don't think we will be able to judge the 2nd part of their collaboration until Aussie Open or perhaps Indian Wells/Miami part of the 2019 season.
Let's be realistic here. Kamau was going nowhere with Pica anyway. She did her patriotic thing at 2016 Olympics and has been average her whole career before and since then.