belt tensioner pulley wore out already?

[nighthawk016]

I replaced my belt tensioner pulley 6 months ago because it was making a horrible rattling noise. I used a Dayco Noslack pulley (#89204) Everything was going good up til recently, the tensioner is starting to make the clacking noise again. I cant be replacing tensioners twice a year.

I need to find the reason why my truck is destroying them so quickly, do anyone have any ideas? I know it does bounce around quite a bit at idle and I checked it shortly after I noticed the noise coming back. Could this be why it is wearing out so quickly?
https://www.youtube.com/watch?v=2UJ9LVRs4fI