Call of Duty Black Ops: Why don't MLG Pro players use Tactical Mask Pro?

I've realized BO MLG Pros players really only stick with Ninja Pro. I know Hacker is not useful in MLG play, and Second Chance is banned, and Marathon just dooes not stack up to Ninja, but no Tactical Mask Pro? I saw people Concussion Grenade the hell out of people in MLG play. I think it's a good 3rd perk for an MLG's job. So why isn't it used?