He knew Fat Tony and he knew John Sullivan. But like you say Tommy he must have over-estimated his weight cos when it came down to the showdown the most vicious killer in his own crew had switched to Coonan and when Tom DeVaney got popped he was left with no choice but to reach out to Eddie who either flat out refused to help or genuinely didn't know why the Ginnies had decided to encroach on Mickey's terrain.

Basically Mickey misjudged Fat Tony just as he underestimated Coonan. But he certainly had balls and is fondly remembered by the old timers. Bring Coonan, Sullivan and Featherstone into the mix and you may even end up with a good old Irish brawl as those wounds run deep, even to this day. but that's a whole other topic .