If you're not in it for the -2s, then there isn't a whole lot to get excited over controller-wise...
So one round you slowed him, but he still bashed the melee guy standing next to him.
The next round you knocked him prone, but he stood up and still bashed the melee guy standing next to him.
The next round you circled around (so as not to get any of your allies in the blast) and dazed him with your color spray. But he still bashed the melee guy standing next to him.
The next round you immobilised him, but he still bashed the melee g standing next to him.
Finally you twist of spaced to put him three squares away from the melee and slowed him too. Great! Now we're getting somewhere. He'll have to either ready an action or delay, so he can bash the melee type when it steps up to him.
Alternately, the melee type could get in a free ranged basic attack. Woopy!
In four out of five different attacks, the end result of the 'control' was diddly/squat except to prevent movement (which unless you have a highly mobile defender is a non-issue), and grant combat advantage (dazed and prone).
Iilusionary Ambush + Psychic Lock + Marked by your defender = -6 to hit. If the monster hits on a 13 or higher, now suddenly they hit only on a 19 or higher. That's a big difference.
Making him lose a move action? Not so much.