Keeping multi-posting. Again. %)
It's not a question of block, as it seems for me. But the question of random. And even more. A shield is very specific weapon. I don't know how much a tank needs Defense stat (it's the main stat of a shield, i hope there's no discussions about it).
For example, Lady Devious works with a strange shield, which is orange, but also it's "old" shield... It has less Defense than a violet "Blood Gods" shield of 55...
And You are know: Lady Devious works fine. It's oedi's work, but not a question of some luck or something like that.
But then let's consider the grey shields. The difference of this Defense stat ... This difference in hundreds!
So, i think, even if top-tank gets "right" shield type in the Pits, it's not a "right" shield anyway.