Bell Centre is a huge arena with capacity for hockey 21,273.
Never been there though but from information online I've noticed that it has a very low capacity during concerts.
For example,
Rihanna concert at Bell Centre only 10.778 tickets available but her concert at Staples Center in LA had 19,992 tickets available and Staples is a smaller arena. These were end stage concerts and the stage size was same in both venues.

Rihanna is not the only example. A common size arena stage altough they varies a bit in size should not reduce the capacity so drastic as it does in Bell Centre.
Any thoughts?
Thanks.