By my count, the current incarnation of MM sports three girls with actual talent, four or five that might develop into useful pieces, and the rest are either girls who are hopeless or have over-stayed their usefulness. Some of the girls fall into multiple categories, tbh.
Sakura is one of the best singers the group has ever had, so no issues there. Maa is solid all-around, and one of the most interesting girls they've had in a decade. Mizuki has become a solid, if uninspiring, singer. I think DJ is right to note that she's massively over-worked, and she would probably be better carrying a smaller load. I disagree with Madara's view of Fuku as a leader, as I would place near the bottom of the list. I will grant that she's leading the least talented group of girls of any previous leader, but that doesn't excuse the fact that Anderei is dead-nuts-on: this group has no spark, and offers little to hold much interest. I think she's a big part of that.
Miki and Maria both offer a different set of positives, and both show promise moving forward. Miki as a sort of bi-lingual Yasuda jack-of-all-trades, and Maria as a visual center. Miki has steadily improved in all areas from the beginning, and Maria does enough, well enough, for a pretty girl with some personality. If I was advising the group, I'd actually have her focus more on developing her personality over singing and dancing. Yoko is a wild-card, and if the light switch ever clicks on for her, she could become a powerhouse. I love her attitude and seemingly endless joy for being in the group, which makes her the girl I'm most excited about in MM right now. Kaga is probably all she's ever gonna be, but she's acceptable filler and is so damned likable.
Which brings us to the rest: I'm okay with Ayumi. She's a good dancer, has her moments singing ("How Do You Like Japan?" on last year's tour) and is a veteran presence. Her personality is odd, but at least she has a personality. Still, at 21, what you see is what you're gonna get. I wouldn't lose my shit if she left. Erina and Haruna are straight-up dead weight in my eyes, though. Graduating them would be the classic case of "addition by subtraction" because they are both so bereft of talent, and their continued presence only blocks girls behind them from growing with increased responsibility. Haga is slowly improving, but her ceiling is Asami Kono or maybe a poor-man's Makoto Ogawa. I no longer hate her being in the group, and I'm even slightly intrigued by her potential, but if she graduated next week, that'd be fine, too. Then there's Chisaki, who is 18 and therefore unlikely to improve on her limited abilities, and seems to hate being in MM. In short, she's everything that Yoko is not. She could be fired tonight, and I'd be totally cool with it.
I'd love to see the current leadership completely gutted, Maa made the new leader with Ayumi as her right-hand, and one new honest talent brought on board. Sakura, Maa, and Miki can carry the load vocally, and Yoko's role can be increased appropriately to see if she can eventually be one of the top girls to move the group forward. We scoff at the idea of MM becoming a talented group ever again because the J-idol world has moved away from that so much, but all you have to do is look across the hall at ANGERME to see that it can be done, and how good they can be. Sure, ANGERME sells half of what MM sells, but that's the difference in branding. If the current lineup of ANGERME was called Morning Musume, they'd sell better than they do.