The second name is short for the older English name "bullherd" or "one who herds bulls". Since my tiny detective is a police Homicide Lieutenant he commands or "herds" a team of bulls (bulls is a common slang term for "police").
So this is your brain on writing--a lot like your brain on drugs, but not as much fun. Coming up with cute and meaningful things like this hero's name without even trying is kinda amazing. In centuries to come when students of literature ponder my little detective entertainments, they will argue whether the name Max Bullard was a tribute or a reference to my cousin Max Billard, or whether it was a cleverly ironic construction referencing the hero's size and rank.
Neither analysis of the name by scholars would be correct. I picked the name out of the air without any thinking involved at all and would never have realized its cleverness had not my cousin Bill started me thinking.