The controversy was actually by the great statistician/geneticist R.A. Fisher in the 1930s -- and the criticism was that Mendel's experimental results were too

The controversy was actually by the great statistician/geneticist R.A. Fisher in the 1930s -- and the criticism was that Mendel's experimental results were too close to his theoretical results, not that Mendel was an "outsider". It wasn't necessarily conscious fraud on Mendel's part, but once you see a pattern it is easy to discard "bad data" that doesn't fit it. That's why modern experimentalists tend to "blind" groups during the data collection phase.