I'm an enroute controller and was wondering why a lot of times, the A320 can't (or won't) fly what I consider to be, a typical holding pattern at altitude.

I won't mention the carrier, but one operator in particular, never seems to keep the plane within "a reasonable distance" from the holding fix.

I realize things like altitude, aircraft configuration / weight, and wind are all factors in this. However, there are times when I have them stacked up from FL290-410 and for whatever reason, the A320 seems to stray a lot farther (especially making the crosswind to downwind leg of the turn). I will issue 15 mile legs to all of them, yet I find this plane more than 20 miles away from the fix and still truckin' away! It ends up being a box-pattern of 20 miles each way or more!

Is this pilot technique, pilot training by that company, or something inherent to the A320, that makes it so sloppy? I'll have a 767 make a tighter turn at a higher altitude a lot of times.

Thanks!