This is probably a very easy answer for a historian. I was reading over the events of Pearl Harbor today when I came to the sinking of the Arizona, in many accounts it states that when the magazines blew it killed 1177 of the 1512 crew on board. When I looked up the details of the Arizona though it always lists the crew as 55 officers and 860 men.
What were all the other men doing on the Arizona that day? There are 597 men on board that day that I can't seem to find a reason for. From what I know of Navy ships (which isn't a ton) they are very spartan so adding 75% more men should have the Arizona just packed to the walls. I'm not saying they weren't there, I'm just curious if the crew size is listed inaccurately or maybe didn't count a contingent of Marines.
Alright, I did some quick google fu and I think I know what you are seeing.
The Arizona and her sister ship the Pennsylvania received extensive modernization in the 1930's. Part of the modernization scheme for each ship was the addition of a substantial number of 5inch AA gun turrets. Arizona also had updated engines and boilers.
I suspect you are seeing the number of crew as built in 1915, not the number of crew required after modernization. I'm seeing crew numbers for Pennsylvania between 1400 and 2000 during WWII depending on the source so I think this is where the difference is coming from.
Online sources are pretty lousy, you might try looking for a copy of Janes Fighting Ships and seeing what it says.