I generally agree with nater's assessment.
Use last year as an example here. Areas that received massive flooding had lower road side counts; whereas areas that received rain but NOT floods had greatly increased road side counts. Rain is good - it creates moisture and lush habitat and a surplus of bugs for birds to eat and grow quickly.
But a monsoon at the wrong time has devastating effects, and its very possible (if not likely) that this occurred in some localized areas mentioned above.
I can say with relative positivity that in nearly 25 years of hunting here in MN that wetter springs often produce more birds than ones that are riddled with severe drought.
The one aspect that I can concretely agree with is that mortality among adult pheasants the past two winters has been nearly nonexistent. When I was turkey hunting this spring, there were a lot of adults around. These fake winters are certainly reducing the amount of birds that succumb in the winter months.