Rousey has always been a largely one dimensional fighter, she just happens to be World Class at that one dimension and up until the Holm fight had simply not faced someone equally as skilled in a different aspect of MMA who could make her fight out of her comfort zone. McMann was arguably equally as skilled a grappler (though lacks Ronda's submission skills), but like many MMA fights between two great grapplers their skills somewhat zeroed each other out and it came down to who could win using the other skills sets (in this case knees from the clinch).
Tate is a pretty well rounded fighter who is good at everything, but not great at anything. Combine that with her toughness and tenacity and you have one "game" female fighter. I honestly still think that with a better game plan she could beat Rousey if they fight again as she showcased the ability to out strike Ronda and even take her down in their second fight; but for some reason kept insisting on clinching up with her (which is NOT where you want to be with a World Class Judoka) which lead to her getting thrown and eventually submitted. It was Tate's well rounded skills and toughness that allowed her to take Holm out of her largely one dimensional skill set dominance that she enjoyed against Rousey, not some sort of intentional "flop" on Holm's part.