As I Explained in the summary, most of the tags for the monster spawner doesn't work. Like Delay, MinSpawnDelay, MaxSpawnDelay, SpawnRange, SpawnCount, MaxNearbyEntities & RequiredPlayerRange.
What I thought it would do:
Just as the wiki said these tags would do, like shorten delay, Causing it spawn again & again in quick succession.
What really happened:
Nothing, It wouldn't even spawn anything.
How to reproduce:
Put in this command:
setblock ~ ~ ~ mob_spawner 1 replace {Delay:100,MaxSpawnDelay:100,MinSpawnDelay:100,EntityId:"Entity",MaxNearbyEntities:100}
I guarantee you these work (however the RequiredPlayerRange works but the spawner appears still active) as I am using them on my multiplayer creative/survival/adventure map.
Malformed command, please check your syntax.
Here's a nice little guide for you:
http://www.minecraftforum.net/topic/1969520-17-using-summon-give-datatags-in-map-making-tutorials/#advanced