What happened to Sakura? Where did Kishi fail?
Right now, she is regarded as a weak link and nobody gives Sakura a second thought, except maybe a few fanatics and some hentai loving folks......
Obviously, Kishi wanted team 7 to mimic the legendary Sannin. Arguable the strongest trio ever, and even though Tsunade would ultimately lose to both Orochimaro and Jiraiya, she still would/could have made their life a living hell. Jiraiya said her and the Kyuubi were the only things which had seriously ever injured him. She was no burden and contributed to the team with her great medical techniques (both offensively and defensively), her great strength, and her amazing chakra control.
All of this was being passed down to team 7, and in part one everything went according to plan.
Sakura was slowly being build up to be a highly intelligent shinobi, who had great chakra control, great stamina, and was diagnosed as a genjutsu type ( all the tools to become a dangerous threat).We have witnessed most of this doing the chunnin exams, when she answered all the question during the written exams, how she took all the mental damage from orochimaru, and brought either Sasuke or Naruto to safety, and most importantly she could dispel a genjutsu, which was noted to be on elite jounin level.
Lastly, she was trained by the fifth hokage in 2, 5 years! Perfect time to evolve her skills to the next level, and nobody would complain if she became a mix of Tsunade, Kabuto, and kurenai.
So, a great close range fighter with her strength and medical jutsu, in which she could screw up the nerves of her opponents and use poison as part of her inventory , plus she could cast genjutsu anywhere. This way she could have kept up with naruto and sasuke, and not be a complete burden.
So what went wrong?
Right now, both Naruto and Sasuke left her in the dust, and all sakura can do is cry and moan about how pathetic she really is. Her only impact in this story is to watch Naruto and Sasuke from the side lines, and actually hinder Naruto in what he needs to do i.e poison Naruto instead of sasuke, and being so delusional she thinks she can take Sasuke on by herself.
She is so worthless she made Sasori look an amateur, the guy who took out the kazekage with iron sand, by himself. It’s like her characters development stopped after that fight and Kishi just gave up on her or worse simply forgot. This was the time to slowly expand on all the things Sakura learned during the time skip. And after hundreds of chapters it seems she showed all she had in the Sasori fight and that is very disappointing. It would have been much better to give her flashbacks like Naruto, and upgrade her piece by piece.
Finally, I think the ship has sailed right now and she will forever play second fiddle to all the mid/top tier guys in the story.