I'm watching some TWD clips on youtube right now and there's like 50-70 walkers here (first time they see a herd). A part of me thinks Rick's group could've easily handled this. After all, they were still in relatively good shape in terms of manpower and they could've maneuvered the walkers around the cars for easier kills.
My feelings exactly, they had a learning curve issue
Meanwhile the herds are massive in the later seasons and they somehow knock out like half of them with ease. Hell, even the Alexandria one was easily decimated once they got their shit together.