I am going to take another approach here, and put the status of the narrations to one side.
This dude is clearly showing off the virtues of 'Ali (RA). There is no reason for us to be overawed because we recorded his virtues before the Shia scholars. Our scholars have also gone as far as putting together treaties on the virtues of 'Ali. We have no qualms attributing such warrior-like qualities to 'Ali. In fact it is obligatory we do so providing the narrations meet the required Hadith criteria set down by the Hadith masters. It's suffice to say 'Ali is one of the greatest Islamic warriors in our history, if no THE greatest. Abu Bakr, and 'Umar do not equal 'Ali in this feat.
The victory of Ali ibn Abi Talib at Khaybar was more than just about being a warrior. It was about leadership. With the same group of men, could Ali use them to bring victory and take Khaybar, at a time when both abu Bakr and Umar one after the other, with the very same men could not? It also speaks volumes about the one through whom Allah wishes to bring victory. Ali ibn Abi Talib was ill, yet, Allah had decided that it was only through him the Muslims would gain victory. Allah , the Almighty, could have allowed Abu Bakr, or Umar to bring victory, yet a statement is made on the one whom Allah favours above the rest.
a) The Prophet (SAW) appointed them with the banner/flag. It's safe to assume the Prophet (SAW) did appoint them because if one studies all the authentic narrations of the battles, the Prophet (SAW) would personally appoint different companions with different positions. No one would ever self appoint especially Abu Bakr, and 'Umar. Anyone who has studies their biographies will know they were very subservient to the calls of Allah (Qur'an), and the Prophet (Sunnah).
The reality is, the situation becomes much worse if one believes Abu Bakr and Umar were directly sent by the Prophet (saw). Given the magnitude of the statement made by the Prophet (saw) that Allah had chosen a man to bring victory for the Muslims, and the miracle he performed to cure Ali ibn Abi Talib, he would have known and been aware that both Abu Bakr and Umar would not be successful, and that it was only through Ali ibn Abi Talib that Allah ordained for victory to be granted at Khaybar.
When i first came across this Hadith in Tabari, i thought that it must be some sort of weak narration. There were many prominent companions at the time, far greater than Abu Bakr and Umar in the battlefield. Neither of the two in all the battles that they had partaken in Islam can be seen to have contributed in any notable feats of bravery. If there is one, its authenticity is questionable or it is a one-off. Yet we find Abu Bakr, and then Umar being sent one after the other. The Messenger of Allah (swt) knew they would not succeed. One would have to question why the Prophet (saw) did not immediately cure Ali ibn Abi Talib and send him? He wanted to demonstrate first by sending Abu Bakr and then Umar that there is a difference between the virtue, the certainty, and the blessings Allah places between them, and between Ali ibn Abi Talib. While the two, one after the other could not do anything in Khaybar, but had to run away, Ali of all people, who was too ill to even fight, is cured by virtue of a Miracle and the produces one of the greatest performances on the battlefield.
'Ali actually tells in an authentic narration Abu Bakr would beat everyone, and leave them behind when it came to doing good deeds. There is no bigger good deed then pleasing the Prophet (SAW) by obeying his every command. In short, the Prophet (SAW) trusted them.
This is not Hujjah upon me. Part of a debate is to agree on sources you can both ascertain to be true.
The narrator probably didn't mention this explicitly because it was 'Ali who stole the show.
We have traditions from Tabari (and it is relevant here if they are strong or weak, because i do not see it important to distinguish how they obtained the banner) whereby the Messenger of Allah (saw) had a migraine and was unwell, and that Abu Bakr, followed by Umar, took the banner instead. The only authentic tradition on this issue is silent in how they obtained the banner. However as i have said before, claiming the Prophet (saw) gave them the banner first is extremely advantageous to proving the superiority of Ali ibn Abi Talib.
According to (1) Abu Kurayb- (2) Yiinus b. Bukayr- (3) al-Musayyab b. Muslim al-Awdi-(4)'Abdallah b. Buraydah- (5) his father [Buraydah b. al-Iiugayb], who said: The Messenger of God often had mi- graines and would remain a day or two without coming out. When the Messenger of God encamped at Khaybar, he came down with migraine and did not come out to the people. Abu Bakr took the banner of the Messenger of God, set out and fought vigorously, and then came back. Then 'Umar took it, fought with even more vigor than the first fighting, and then came back. When the Mes- senger of God was informed of this, he said, "By God, tomorrow I shall give it to a man who loves God and His Messenger, whom God and His Messenger love, and who will take it in humble obedience." [Tarikh -At-Tabari, English translation, Volume 8, p119-120]
b) The Prophet (SAW) entrusted them with the banner before 'Ali which, again confirms their seniority in rank.
Ali ibn Abi Talib was ill and had an eye infection, and at the time was not even eligible to fight, and thus this point has no weight.
c) The Prophet (SAW) didn't see them as cowards. Why allow, or not refuse at least them from taking the flag/banner, ands charging the enemy if you know they're only going to end up embarrassing your entire army. Shias are always using weak narrations to confirm they ran away during the Battle of Uhud. These narrations confirm they were running in the face of death.
We are not talking about Uhud, and i am aware that narration is disputed. Rather our topic centres on Khaybar.
Shias would exercise their minds before sharing such narrations that effectively refute their own stupidity.
Only in a parallel universe would this tradition support the Sunni, rather than the Shia narrative. Rather, it emphatically supports the Shia narrative. If you see, i had only quoted supporting traditions to prove that Abu Bakr and Umar went, did not succeed, and were forced to retreat. I did not quote the other traditions so that the Matn of the traditions could be verified as true, save what was in the Saheeh tradition.
I will stipulate once more how this firmly supports the Shia version:A. Allah could have granted victory through Abu Bakr as well as Umar, but chose not to. Not only did Abu Bakr possess the very same soldiers as Ali, but the fact he was unable to take Khaybar is a clear demonstration of his leadership, bravery, and ability in battle compared to Ali ibn Abi Talib.
B. If for sake of argument, we say that the Prophet (saw) did appoint them, would this show their seniority ? Absolutely not. The Prophet (saw) knew full well that it was only through Ali ibn Abi Talib that Khaybar would be taken, yet wants the world to witness, there is a difference between Abu Bakr/Umar and Ali ibn Abi Talib. The very fact we coincidentally see them, one after the other, with the same soldiers sent to battle and retreating is very telling.
C What did Ali ibn Abi Talib possess that Abu Bakr and Umar did not? He had the same soldiers , did he not? The difference is the Yaqeen of Ali ibn Abi Talib, the fact Allah favoured him above Abu Bakr and Umar, and his bravery in challenging the most fierce warriors of the Jews, in addition to his superior leadership skills over the soldiers he was sent with, should stand witness of his rank , compared to theirs.
By saying this i mean no disrespect to them in any way.