It kind of is. You take away 90% of the hitpoints in a matter of 3 seconds.
Worker can almost kill michael solo, just look at goiko's replay. Naturally defender and worker can kill him together.
The issue is: Crush gets weaker as Michael's hp gets lower, and his last spurt rage is enough to kill a defender in about 20 hits. For this last spurt, all the damage done to him will be by physical damage, because 10% of his current hp at that point is insignificant. Can shandris actually deal enough damage to michael before he does those 20 attacks?