I also get pissed when my food plots or tree plantings don't go as planned, but my hunting success doesn't seem to be tied to how good my food plots and trees do that year. My worst food plot years sometimes match with some great hunting, and the opposite is also true.
I'm betting you will see a bunch of switchgrass next year in those areas. You could always frost seed those areas early next spring to give them an extra shot of switchgrass seed if you aren't sure. My CRP blend that contained switchgrass was a solid mat of oats, clover and perennial grasses the first year. It was way thicker than your weeds pictured, and I couldn't clearly see any switchgrass in that thick mess of grasses, clovers and weeds. Then the next year the switchgrass really took off and it looked like I knew what I was doing.