It is possible that you think Polymorph is the only way to control mobs. However, it is not. Even though it is the most effective single-target CC we have, there are other options for mages to prevent mobs away from ourselves and others.
Snares Slow, Frostbolt, Frostfire Bolt, Blizzard with Ice Shards . All of them can be useful for kiting or just for preventing a mob from reaching WOW Gold long enough to down that mob. Please think the adds on heroic Erudax.
Roots Frost Nova -- This plants mobs in one spot but still allows them to attack anyone in range, cast spells, et cetera. If they are used by stupid people, it will be so dangerous. Pro tip: never use this within whacking distance of your healer.
Freezes Ring of Frost, Improved Cone of Cold, Shattered Barrier ¨C All of them are good for keeping mobs in a specific spot and incapacitating them for the short term. However, normally it is for improving a frost mages DPS.
Interrupts/stuns Counterspell, Cheap WOW Gold, Deep Freeze -- Though they are not technically CC spells, these are useful for temporarily stopping a caster from casting and can be great for repositioning caster mobs, bringing them closer to yourself or the tank. Control is control.