I am calling BS! I think the problem with Tiger's ability to hit the long ball like he use to. Tiger has been hovering around 292-293 yards for the past 5 years or so. He maxed out one year at 311. Then he went and screwed up his knee. That is were his power issues are from. He can't rotate his hips as fast as he use to because it causes him to snap his front knee straight.
As for the MYTH that muscles call inflexibility, that is total BS. Weight lifting increases range of motion, not decreases it. Look at the Olympic Squat competition. Those guys get their butts near their heels when they squat. They all have huge legs, but a ton of flexibility. So weight lifting does not decrease flexibility.
Now does he work out too much compared to working on his golf game. Not sure. I watched an interesting video of him and Rory at their personal match they did last year. Their mutual friend and former NFL player was commentating the match. I think it was over in China. Well Tiger was talking to Rory about the off season , and about how he has to go to the gym to rehab his body, especially his back, and do a lot of injury prevention stuff.