All that is true, but with him she learned to be more patient, play with more margins, something she had never done before, and started counterpunching with her BH DTL, which is such a great shot for her and lifts her whole level when it works, which certainly wasn't the case today (I've always thought Fissette is a good coach, so I hope he won't take the "you need more margin/play only CC" approach) and her peak was never higher than when he was coaching her, and for the kind of tennis she plays that is so so important (won her 2 slams). I don't mean it in terms of consistency, because Osaka is too moody and lacks dimensions to her bashing to be a consistent player, regardless of her coach. I remember right after she won IW, she was crying in a match in Charleston against Georges, so that shows, but imo Bajin is good at maximizing players abilities without changing the nature of their games, usually a road to disaster. ALL the players that have worked with him have improved their results. People might make fun of his time with Mladenovic, but she was barely winning matches and ended up having quite decent results in a short time. To put it another way, would Osaka have won more slams if she had stayed with Bajin, even if she kept throwing stinkers here and there ?I agree with the bolded, but she was still really inconsistent under Bajin (losing streaks, periodic bad form, etc.) and had some questionable losses at Slams. Easily folding against Halep, Keys and Kerber—that match against Kerber I vividly remember because it was just tactically inept from her end --- Osaka didn't want to do anything to make Kerber uncomfortable and thought she could outhit her from the baseline on a grass court, well, we know how that turned out.
The main difference is that now, she's higher ranked, and will instead lose to lower-ranked players that can exploit her weaknesses in the early rounds. Like her last four Slams have been atrocious --- 3R, 1R, 4R, and 3R. Osaka's peak is so outstanding that I forgot how bad her base level actually is, which is concerning. Like that backhand can turn into a Keys-esque mess without any warning, and don't get me started on that second serve. Maybe she's just gonna have a Kvitová-like Slam performance for her whole career. For sure she will win more, most likely on HC, but losses like the ones she's had in the past year will no longer be surprises.