Needs more total titles, more slam wins, more stay at #1. She's great no doubt, but a lot of hype for her being the best ever, yet can't pull a consecutive dominance at the top a la some of the greats. Frankly, given the pathetic state of the WTA if she only wins 1 or 2 slams next year (assuming no injury occurs), I'd question her "highest level of play" credibility big time.
Roger Federer. Paolo Maldini. Tom Brady. Wilt Chamberlain. GOATs.