Let's list Kishi's development failures with Sakura:
1.) Best chakra control in team 7 in part 1, but no element given. He's only used her chakra control to heal.
2.) Natural affinity for genjutsu, but never given a chance to show it off. Given her chakra control Sakura should have been a monster when it came to genjutsu or at least above average like Kurenai.
3.) Combat trained by Tsunade, but after the Sasori fight she's never been involved.
4.) Has deduction and analytical skills on par with Kakashi, she did figure out Obito's jutsu after seeing it only one time and before Kakashi, but she's never been given a chance to use those skills in battle.
5.) Monster strength, but never been given the chance to live up to her nickname of Tsuande Jr.