It doesn't hold true to the characterization. Moiraine could not do what Cadsuane did, or play off Rand the way Cadsuane did. Cadsuane's asset for the purposes of her interaction with Rand was her long and unique experience. She's seen it all and done it all, and the fact that she is Aes Sedai is not nearly so important as her life experience and perspective. I would even venture so far as to say that the only narrative reason she is Aes Sedai is because no one else could have done what she did to get the experience and knowledge she brings to the table.

Moiraine was a kid by Aes Sedai standards, and as far as mentoring goes, all she had to offer were skills and experience that farmboys could not have gained yet. As it stands, if someone were to reach back through time and yank Moiraine back just before she falls through the doorway, she would be useless in the contemporary period. She was not nearly as good, smart, competant or loyal as people remember her, and full of the arrogance of her position. Cadsuane's arrogance comes from a long string of genuine successes and confidence in her abilities. Moiraine's was totally unearned and derived a lot from her self-perceived superiority to her charges. She was better at pretending to be in control than actually controlling anything.

But it was real. She was THAT good, though in Rand's case, it was because he let her. Pre-Rand, that is a pretty fair summation of Cadsuane's place in the world. She was the top Aes Sedai, and the Aes Sedai were the top dogs in the main part of the world, and even the other known cultures held them in a certain awe.

That would be a disappointing case of juevenile wish-fulfillment. There are not enough important or powerful good guys in adversarial roles with the main characters. To have everyone who looks cross-eyed at one of the protagonists turn out to be a petty, selfish loser or a minion of the Shadow is too easy.

Cadsuane turned up right after Rand had the single most traumatic experience among the "slings and arrows of outrageous fortune" which drove him to become "Dark Rand" and hit the nadir of his character which he reached in tGS. Her narrative purpose was to articulate for the readers exactly what the problem was with his behavior and attitude. Her role regarding Rand was to be something of a humanizing reminder, like a court jester or the slave who would stand behind a triumphant Roman general to whisper in his ear "Remember you are mortal." The fact that she failed to reform Rand or change him demonstrates that he was beyond the help of even this most competant and capable individual. No one could help or change or save Rand - he had to do it himself, and find his own way back.

Regarding Moiraine's own capability for this role: non-existant. She would never have learned in time to see what was wrong with him, and she even gave him nudges along the dark path. Cadsuane guessed at that which is why she expresses irritation with Moiraine back in one of her earliest PoV. Moiraine's adversarial role helped teach Rand suspicion secrecy and not to trust his advisor. That was why Cadsuane made such extravagant promises to Rand when she set the conditions under which she would be his advisor. She IS loyal to the Tower and does see the Tower as the most important thing. I would even go so far as to say that she dedicated herself to saving Rand because the White Tower would be destroyed if he loses to the Dark One or lost himself. However, that would not be possible if he could not trust her and she could not have access to him, so she had to promise him that she would not repeat Moiraine's errors.

Moiraine only swore to obey Rand when she ran out of options. Look at what happens in tFoH before she makes that promise: Rand lays out his plan, of which she thoroughly disapproves, and demonstrates his indifference to her opinion on the matter and the Wise Ones refuse to cooperate with her attempts to thwart him. She knew that her time left to advise or influence him was limited, and that if he succeeded without her (as he almost certainly would - his reasoning about the overwhelming force he possessed & its certain effect on the wetlanders was dead on) and in spite of her opposition, she would lose all credibility. The only way to keep her influence and authority was to stick with him and the only way to get him to listen would be to swear to obey him. She never promised to put her loyalty to him over that of the Tower and tacitly admits to Egwene later that her loyalties are unchanged. Her air of mystery was cultivated on purpose. She was not actually mysterious but actually rather simple and shallow. She was not amazingly competant, capable and all-knowledgeable, she simply pretended that she knew everything already and that everything that happened was according to her design. She was far better at spinning events to make her look good than actually achieving anything. Her single greatest accomplishment - finding the Dragon Reborn - took almost 20 years, without anyone actively opposing her or hiding him. Much is made over her killing two Forsaken, but in both cases, she basically shot them in the back while they were concentrating on Rand. Nynaeve may not have any fatalities to her credit, but she blows Moiraine out of the water when it comes to their track records confronting Forsaken.

Think back to EotW, when the group was reunited in Caemlyn, and then imagine their little conference in the Queen's Blessing taking place among the characters at their current levels of power and ability, and their being told that the city they are in is surrounded by a secret, hidden army of Trollocs and Myrdraal. Moiraine's plan of "sneak out of the city using the Ways" would have everyone else laughing at her and putting her in the corner with a doll to play with while the grown-ups discussed the best way to handle the situation that would result in maximum damage to the the Shadowspawn with the optimum political gain and minimal casualties for their side!

What does Moiraine REALLY have anymore? Things that all the other channelers take for granted would be legendary feats to her eyes, and all of them possess superior military & political power (even Nynaeve: Lan > no Lan; or to put it another way: Lan's poontang + marriage vows > Lan's warder bond + oath of fealty. Regarding political power, Rand, even at his worst, trusts her more than he ever does Moiraine and Elaida's old job is Nynaeve's if she ever decides to go take it up. Whereas Moiraine has pretty much zero personal political power. What she does derives from House Damodred whose current big-shots are more beholden to Rand or like him better than they do Moiraine).

Moiraine will be important only for what she may get out of her sojourn among the 'finns, and for how her return is perceived by the important characters, not for anything she already had before her "death".