I know he has a big following on the baseball side, but many of the Ted Williams fans that studied Ted, disagree with Mike .
I'm not sure who the many Ted Williams fans are, that studied Ted and disagree with Epstein. But I prefer to take Ted's word for the correctness of what Epstein teaches. In the only letter of recommendation ever given out by Ted Williams for hitting knowledge and instruction Ted says:
"...I see Mike frequently and have parried batting technique and theory with him — both the physical and mental sides — on many of those occasions. I'm a tough guy to please and impress, but I believe Mike comprehends and teaches the science of proper hitting as skillfully as anyone I have run across in all my years in baseball."
The reason I use Epstein's material as a foundation for what I teach, is not because I'm enamored with Epstein (I've never met or talked with the guy). It's because he was a personal friend of Ted and has first hand insight into Ted's views on hitting. IMO Ted had some of the best swing mechanics ever, over their many years of friendship Ted conveyed that information to Epstein and IMO Epstein's material is based on what Ted believed.
I would refer the fan's of Ted that don't think he's teaching Ted's swing correctly, to the video clip of the Fleck kid. It looks pretty similar to me.