I was wondering about your paladin tank and how he was timing his avengers shield/judgment?
I have been the main tank on guild first kills in two separate guilds now on this guy and have never had an issue with shield timing or not being able to be in judgment range if for some reason my shield misses/bad timing.
Starting the fight off with avengers shield is a bad idea. Concecrate should be placed in leos's path before he breaks loose and judgment of righteoussness should be used to secure initial aggro. Avengers shield should be saved for when whirlwinds end. He/She should watch their boss timers very closely and start the avengers shield cast 1 second to half a second BEFORE whirlwind ends. The shield should hit just as leo's aggro resets and I f the dps is being intelligent that should be more then enough to stick leo to your paladin tank.
If your paladin tank has low hit rating then it is very advisable for them to make every effort to be in range of judgment as well when whirlwind ends. Three points in pursuit of justice helps with this greatly, short of that boars speed on their boots also helps.
If you don't have the paladin on him I'm not sure your effective health set is the best for this guy. If you have a gear set more oriented towards threat I would very much recommend using that gear set instead. Fully raid buffed I am at about 22.5k health in my EH set, on this fight I go down to about 18.5k. The loss of health/armor is very worth the added threat imo.