skip the tenderizer. You'll be cooking to tender all the way though the brisket, so giving the outside a head start seems pretty weird.
What size brisket are you cooking?
My standard advice on learning to cook a new piece of meat, is to go hotter and watch it closely. Essentially, the same processes occur, just a lot faster, making them more observable. The other nice thing is you can let the wsm run without minding, eliminating a lot of worry, so you can focus on the meat.
The key problem with brisket is pulling it off too soon. It will be tough and dry and will make you think you overcooked it. If you cook it low and slow, you may run out of time, or panic because nothings happening, etc and you'll end up with an underdone piece of meat, and you still won't know what you have to do to get it to tender (5 more minutes or 5 more hours?) or what it felt like as it approached tender.
Once you know tender, you can then back down on the temps for future cooks.
good luck HTH