It -is- pretty si+*mple physics. If his foot is moving forward into the drum more than it's moving down onto the pedal, and that seems the case, it's gonna cause the issues. Not arguing velcro, but given the fact that he was moving sandbags around with his kick foot (also no pun intended), I was giving him some more dramatic solutions.
In any case, I'm confident some idea presented here will help him, and that's the idea. If he uses velcro and none of my ideas, I'd be completely happy.
Peace?
ABSOLUTELY Peace man, I wasn't putting any ill will in a personal manner here, just a professional manner with some FIRE.
If you think about a sandbag, even though you have the sand contained, it moves within the bag, creeping ever so slowly forward rolling the bag as it goes. To use an OBJECT you would need a solid object, which in the drumming world is unsightly, unprofessional and unnecessary.
Velcro is SOOOO cheap and easy to find and SOOOOO easy to use. That's probably why DW puts Velcro on the bottoms of their pedals, cuz it WORKS.
The reason I'm so passionate about this subject is, before Velcro was a popular pedal addition, I did ALL of the things mentioned here and then some, to get my kick not to migrate across the stage. And being as I STILL use Vintage drums, which do not HAVE the kind of awesome spurs that are available today, I had ALL KINDS of issues making the kick stay put until I put Velcro on my pedal!! Seriously, it CURED the creeping problem IMMEDIATELY!! I NEVER had to deal with it again. I even put a piece on the Hi-Hat pedal's bottom, just to lock it to the rug. It's AWESOME stuff!!!
As long as you use a rug under your drums, and you put Velcro on the plate of your pedal, it simply CAN'T move. Any pressure on the pedal INCREASES how Velcro holds to the rug, so essentially, the harder you hit, the MORE Velcro holds to the rug.
.
.