Theory: Obito did not slip through the rock using Kamui
This topic was at the center of a debate after chapter 602 came out.
Some alleged that Obito unknowingly used his Kamui ability to "phase" through the rock that he was found next to in the tunnel.
Others alleged that he simply fell away from the rock when both broke through the ceiling of the tunnel.
Well let's have another look at what Madara said:
Alrighty, so we have:
"It's a miracle that you're alive" <- Well this doesn't help anything because it would be a miracle in both cases, whether he phased through the rock or was lucky that their trajectory was slightly different.
"It's almost as if you were able to slip away from it" <- This is the main "evidence" used by those who claim he unknowingly used Kamui to "slip through" the rock. Opponents pointed out that it says "slip away" and not "through". Thus, this once comes down to opinion.
"You were lying ... next to the rock" <- This one highly favors those who believe that he got lucky in that the rock landed beside him instead of on top of him. Why? Because if he had simply slipped through the rock using Kamui, he would still have been positioned with the rock on top of him (okay, well he'd sorta be IN the rock, or rather parts of him touched by the rock would be in the other dimension) ... which would have been an interesting sight.
"But half of your body was crushed, indeed" <- Well this happened when Obito saved Kakashi. Although some have used it to provide a third explanation that both Obito and the rock fell straight down through the ceiling of the tunnel and then the rock rolled away after impact. So I just lump this one with the "lucky" theory.
So, while everything mentioned above would still leave the debate to opinion, we now have solid evidence that Obito did not gain the powers of the MS until the latest chapter, here:
As Kakashi deduced in their fight with Obito, his ability to "phase" and his ability to absorb/fire out objects are one in the same Jutsu, that is, Obito's Kamui.
Kamui is solely a MS power. He did not have MS until the traumatic events of the latest chapter. Thus, Obito did not use Kamui to phase through the rock. He got lucky and fell away from it when they broke through the ceiling of the tunnel.
And that's about it! Feel free to express opposing opinions, just back them up with some evidence (or at least sound logic). Thanks! :D