This is why i dont trade YM. Its been around longer than ER2 and EMD but liquidity still sucks. Its not suitable for serious trading imho.
The number of contracts is relative to the market. This type of irrational move CAN occur on almost any market. No matter how "serious" of a trader you are, you are subject to this possibility in many markets. With keyboard or mouse entries, we're all subject to errors that can occur in less than a second, right ? Just the other day I paid a large bill online and whoops, I selected the wrong account to pay from and within seconds I was severely in the negative in that account.