Two ideas on Masei, one a great yesod in tefilah, one a great Meshech Chochma:
1. Someone who killed b'shogeg must stay in an ir miklat until the kohen gadol dies. The Mishna writes that mothers of kohanim gedolim used to deliver food to the ir miklat so that the killers would not pray for their children to die so they could get out. Why is the sentence of the murderer tied to the kohen gadol? The gemara explains that the kohen should have davened for the killer to not suffer such a fate.
The gemara says that even if the kohen gadol is appointed just before the verdict on the case is announced, the murderer must still stay put until the death of the new kohen gadol.
Why is this new kohen gadol held responsible for not davening when the facts of the case are in already before he is appointed? What good will his prayers do at this point? If the murdered committed a crime, he will be sentenced; if he is innocent he will go free. Prayers can't change what happened in the past!
R' Baruch Sorotzkin (in HaBinah v'HaBracha) answers that when it comes to davening, the facts don't matter. Imagine r"l if a parent or a child is in the hospital -- does anyone say, "Well, the doctor says this is the likely outcome, so there is no point of davening?" Of course not. Tefilah is an emotional response; we don't weigh odds or facts or logic before crying out to Hashem. Here too, if the kohen gadol truly empathized with the plight of this fellow Jew, regardless of whether the facts were in, regardless of whether it was obvious how beis din would rule, he would still cry out on his behalf. To not do so is a pgam in the kohen's ahavas Yisrael and midas hachessed.
2. The halacha is that one must tear kriya on seeing the ruins of the cities of Yehudah. Sha'arei Teshuvah O.C. 561 quotes a sevara to explain why people don't tear kriya on seeing the city of Chevron: since it is an ir miklat and a city for the Leviim to live in, it no longer has the status of being part of Yehudah's portion.
This sevara makes two major assumptions. The first assumption is that cities designated for the Levi'im to live in actually become their nachala. In other words, it is no longer a city of Yehudah (or whatever sheivet) that Levi'im happen to live in, but it is a city that *belongs* to sheiveit Levi as their portion in Eretz Yisrael. The Rambam paskens (Ma'aser Sheni 11:17) that Leviim and Kohanim can recite viduy ma'aser because even though they did not receive a portion in Eretz Yisrael they received cities to live in. This is their nachala.
The second assumption: The gemara at the end of Sota tells us that after churban haBayis there were no longer cities designated for the Levi'im -- even when Ezra returned and resettled Eretz Yisrael. Why not? The Meshech Chochma on our parsha (Masei) admits that he is baffled by the question, but suggests that perhaps it is because unlike in the days of Yehoshua where there was a division of land through the urim v'tunim and each tribe was allocated a portion, Ezra never divided the land between the tribes. (R' Chaim Brisker says a similar sevara to explain why there was no chiyuv terumos u'ma'asros in the days of Ezra even though m'doraysa the kedushas ha'aretz was re-established.)
If this is correct, then the status of Chevron as one of the cities in the nachala of the Levi'im is null and void.
But, you will ask, then why do we have to tear kriya at all -- the status of the cities as "arei Yehudah" is null and void as well? The answer to that is that it is not the ownership of the tribe of Yehudah which demands kriya (why Yehudah more than any other tribe?), but rather it is the cities of Yehudah's proximity to the mikdash which is why we tear kriya for them. It's a geographical reality, not a din in nachala.
See R' Zolti's Mishnas Yaavetz #48 who takes issue with this Meshech Chochma and has a full discussion of the topic.