If the tournament participants eat their catch what is the difference between that and a gaggle of weekend warriors fishing and catching their limits and taking them home to eat. Your implication is the weekend fishermen release the big ones. I'd like to see your evidence on that.
Why would you think the average angler is out catching 4-6 lb fish on average, much less a trophy 28+ inch walleye over a given weekend?
I am pretty sure the tourney anglers don't catch, keep, and eat the majority of their fish. Since that is true, they kill far more fish than the weekend angler who catches 5-8 fish and only keeps their 5 before heading back to the dock.
Tagging studies don't lie. Fish once caught and released are far more likely to not be caught again then they are to again see a tape measure. Hence, the natural assumption is that those fish are far more likely to die than simply being smartened up to where they don't bite on a hook again.
There's no way you could convince me the average weekend angler impacts the walleye population more than the same area would have if there's a tourney in the near future. The numbers are just what they are...