Guys your truely overestimating Rukia's past deeds. First the Arrancar she defeated was taken out when she was released and had surprize on her side it was done purely with a special attack. The "sand Guardian" is weak against water... Ice is frozen water and as such Rukia had a type advantage over it. Rukia has barely fought in between here and regardless of her maybe being good enough to be seated at the start she still crapped herself at the site of a single Gillian in the real world.

The fact is hollows should be much stronger on there home turf and while a normal Death God might get some boost I wouldn't imagine it to be more then a hollow would get in general. It simply seems odd someone who hasn't really trained or fought for most of the series is suddenly killing Gillian in one hit with a unreleased sword and about as much effort as it takes me to swat a fly.

I'll buy Ichigo can do that with his sword in constant release as it is. Renji maybe as he has managed to get closer to captain level by obtaining Bankai and training constantly. Chad and ishada are a long shot as we know they trained a ton but haven't seen enough results to gauge current power. Rukia is a spell caster she's not even close to Captain level and I'd expect any vice captain to have to release to kill a Gillian. Those who can do that and still have a Bankai should be able to take on more powerful foes. As it stands I just don't hold Rukia to being at that level of pure strength/skill right now.

@RyougaZell No its been said to have a 100% chance to become a humanoid Arrancar you need to be a Vaste lorde its also been said if Aizen had that many Vaste Lorde Arrancar that he would have already won its doubtful that even a majority of the Espada are Vaste Lorde much less all Arrancar.