Looking back, he's committed one failure after another, saved only by the wits of his subordinates (and, of course, Ichigo). Besides being "the strongest character", I really can't see why he should stay in the leadership position.
In SS arc, he was completely fooled by Aizen, blinded by unquestioning trust in the validity of the council's word, etc etc.
In Arrancar arc, his plan failed spectacularly.
Now, in the final arc, it's apparently his fault that the invasion is occurring (through the failure to "kill that man".)
And, in none of the arcs, he listens to the words of his subordinates with important insights and ideas.
I just don't think he's a guy who deserves the leadership position.
I don't think he is an incompetent leader i think he knew something was brewing, but didnt know what, i do think however that he is old mistakes are going to be made but weither or not he's up for turning it around is remained to be seen...
With him being completely fooled by Aizen i don't disagree with that, but he had to follow the council's word, you gotta remember that SS was at relative peace his duty was to hold that peace, now its become the fact that the only way for him to be able to up hold the peace is to be on the front lines... plus now there's a new council and he hasn't had to talk to them once, which makes me think they have given him a lot more freedom with the way he runs things..
The Arrancar arc wasn't a failure as such, i mean aizen as we know was a master strategist he knew that yama was a power house and need to be neutralized, which he did, it's not like Yama's plan failed either it worked really well until there was a set back....Yama's plan for the most part was to stall as much as possible for other power house's like isshin, urahaha, yorchi to make preparations, i didn't say ichigo in the power house due to the fact he wasn't much of a power at 1st until the dangai training, only then was able to face Aizen....
There's a lot about yama we don't know, we don't know why he had to always go to the council for decisions, he may have done it threw fear that he'd make a mistake....
Also, yamamoto is not the leader of SS. He is the commander of the gotei 13, that is the limit of his authority. As with any other military body he is subservient to the government he is sworn to protect. Its not like he could have known the chamber 46 was murdered and aizen was playing everyone.
You mean the fake karakura town? I mean, there was a time when things seemed grim for everyone however there is the consideration that the whole thing happened rather spontaneously. For that matter, even though they were mislead to believe the war would happen at least a month after it actually happened they were still able to stop aizen from outright walking into karakura town when he did and it even seemed to take every resource the 12th division had.
I don't think we have ever seen the guy being given any opinions or insights either safe for when he ignored mayuri's concerns about ishida's appearance being an indication of the upcoming holy war and potential apocalypse.
My friend is a big Yamma fan and he actually gets pretty upset when I called Yammamoto incompitent, foolish and unnecessary. A key example was when he was fighting Aizen in fake karakura town and allowed all his captains to be defeated in order to sacrifice them and thus achieving the "ultimate" (sarcasm) attack, which failed anyway. Okay super genius Yammamoto, say you actually survived that blast now that you killed virtually all your captains, what now? I don't know but I thought he would have stood a better chance trying rip Aizen apart with his bare hands rather setting the stakes so unnecessarily and stupidly high. Its almos as if this dude didn't think of the possibility that the attack would fail at all.
Leadership is a tough job. Even if your subordinates give you different ideas, at the end of the day the responsibility of the decision you made rests on your shoulders and you have to think about the potential consequences of all your decisions thoroughly.
In Rukia's case, could Yamamoto disobey the direct orders of his superiors for saving an unseated officer? Perhaps he asked C46 to reconsider their decision because it was harsh and they (actually Aizen) declined. From our point of view, it's easy to judge because we know it was Aizen who gave the orders but what if it was real C46? IMHO the real C46 made an even worse decision which cost them valuable shinigami such as Urahara in TBTP arc, it's not as if they're reasonable men who make sound judgments.
In Arrancar arc, his plan to save Ichigo apparently worked in Aizen's favor and Aizen trapped four captains in HM. But, thanks to these captains, Ichigo returned back to FKT and defeated Aizen. When we look at the big picture, it was the right decision which saved valuable assets for SS. Even if Ichigo couldn't come back to FKT to fight, would it be Yamamoto's fault? Did his subordinates give him insight about the possibility of such a plan?
We still don't know what happened between Yamamoto and VR leader in this new arc, so it's too early to judge. For all we know, this guy could be someone dear to Yamamoto. Perhaps the remorse for his failure to kill that man made Yamamoto more strict as a leader, it was a valuable life lesson.
When Ukitake said Yamamoto was irreplaceable, I don't think he was only referring to strength of Yamamoto. His subordinates trust his decisions, they know they can count on him when they're in trouble and don't know what to do. The worst decision is better than indecision and Yamamoto is kind of man who has the courage and determination to make a decision however undesirable it is, IMHO this is the quality of a true leader.
I agree with Miyagi . It's really difficult to be a leader as you have tons of people advising you, but then you have to decide what to do and what not. You have all the responsibility on yourself and even if your subordinates do something wrong it will be still you who is responsible for the result, because you have a task you must achieve, hence it doesn't matter why this task isn't done or done correctly. Your higher-ups will ask why you didn't do everything to make it be in order. It's the same with politics, when everyone knows how to do it, but when someone gets to the top they suddenly can't do it the way they've talked about it before.
A gree with Ukitake that Yama is inreplaceble now. Yama isn't only the strongest for now, but he is also the most experienced one among all the Shinigami in the current Gotei, thus he will know what to do in most of the situations. Also we know what he didn't do correctly, but I believe it's safe to say that there were tons of things that he had done in a propper way, thus it won't be good to replace him. Later it might be somewhat good to replace him with Shunsui as he might be a great leader, when he understands the need, but as of now Yama is the leader and he needs to be at the top.
P.S. Also, remember how were the Captains interacting between each other at the begining of the SS Arc... If there was no Yama to hold them... I do believe they will try to decide all their problems with power and there won't be anything good in it.
When you've been in a leadership position for thousands of years, you're bound to make some mistakes.
It is not that Yama is incompetent but Aizen very competent.
As for the quincy thing... Yes, it seems this "could be" a mistake. I say "could be" because maybe the quincy king wasn't killed because Yama showed mercy, and "having mercy" isn't a mistake but an honorable trait for a leader to have.