Does Rabbi Yanai argue with Rabbi Hanina? Perhaps he just offered another
possibility? From the language ("Mishum Rabbi Yanai Ameru") it seems that the gemara in
Bavel is discussing the discussion in Eretz Israel, where both Rabbi Hanina
and Rabbi Yanai lived.
I wonder whether it was "common" that ALL the blood of a Korban Toda was
spilled. If I remember - only if all was spilled is the Korban lost and
hence the Lehem. Surely if there was a great crush of all the people bringing one Korban
Toda, and for each Korban Toda there were 40 Lahmai Toda - Albeit only 10
were Hametz - there was a great oversupply of Lehem, and it is much more
likely that some Lehem was left over than that All the blood of a Toda was
spilt.
However - it seems there were different times in the practice of the
general public: we have two very different descriptions of the way the
public and their sacrifices were handled: one description is of great
quantities of blood, which was carried by a chain of kohanim from the
Kabbalat HaDam to the Zerika, with the full utensils being handed from one
to the next and in parallel the empty ones returned; on the other hand we
have a description of only a limited number of people entering at one time,
and only three groups. This may have been the case when the Romans
interfered with the activities in the Beit Hamikdash - and this may be the
situation Rabbi Eliezer referrs to when he explains "B'Derech Rehoka" -
even at the entrance to the Azara, when the Roman police wouldn't let more
than a limited number of Jews celebrate the Pessah properly. In that case
they would also not permit great masses on the 13th to bring their Korban
Toda!
Could it not be that the answer of Rabbi Hanina applies when there were
great masses of people who on the 13th brought their Toda, and there were
Lahmei Toda left over, because all the people around had their own Toda and
lehem to eat and could not eat the Lehem of others; as one explanation of
the shortened period of the eating of the Toda (the day and the following
night in Toda, and NOt the following day also as with other Shelamim) - was
to cause the person bringing his Toda to invite many guests to participate
in the eating of the korban and its Lehem, to partake in the thanksgiving
"Before the Lord" - which was fine on other days, but just before the Moed
there were very many, so there were leftover Lahmei Toda.
Rabbi Yanai showed us the possibility when, even though only few people
were to bring sacrifices, and there was no problem with the Lehem, since
the Lehem could be eaten throughout Jerusalem - we could have Lehem Pasul:
as Rabbi Yanai suggested: in the case where all the blood of one was spilt.
LeShana Tova TeKatevu veTeHatemu
Yeshyahu HaKohen Hollander
(a) It seems that Rebbi Yanai comes to argue, because Rebbi Chanina's explanation is more straightforward and fits better with the wording of the Mishnah, which says that the loaves were "Pesulos." Rebbi Yanai -- who explains that the loaves were actually Kosher -- has to give a forced explanation for the word "Pesulos" and say that it means that they were Kosher but their Korban was not slaughtered. Since Rebbi Chanina's explanation is more straightforward, it must be that Rebbi Yanai argues with it, because otherwise he would not give a less straightforward explanation.
(b) Usually, the Pesul of the blood being spilled occured because the Kohen doing the Zerikah fell down. In such a case, all of the blood would have been spilled. The Gemara tells us that the utensils in which the blood was carried were pointed on bottom, and thus they could not be set down straight, and when they fell their entire contents spilled.
(c) Your suggestion is very interesting! We don't find, though, in Chazal the difference that you describe in the way the service was conducted due to Roman interference. Furthermore, the Gemara later implies that then Rebbi Eliezer said that five Amos from the Azarah was a "Derech Rechokah," that it was so in all times, and not just in the times of persecution.
The contradiction that you describe concerning the the way the sacrifices were handled (that is, whether there were many people inside the Azarah or not) is not clear to me. From all of the Mishnayos in the fifth Perek it is clear that there were overwhelming crowds in the Azarah, and in the same Mishnah which describes the crowds, it states that there were three groups involved in the Korbanos (the third group had less people than the others, only because everyone was eager to join the first two groups).
Thank you and Yashar Ko'ach for your insights! Please forgive us for the delay in responding to you.
Shanah Tovah!