I'm late to the club... I used to believe the conventional thinking of hitting through 3-4 balls in a row and I found Oscar's videos odd looking.
I happened to see Doug King's video on TennisOne about orienting to the ball and talking about angular momentum when something clicked. Here was a normal American coach (not MTM affiliated as far as I know) basically describing a similar shot as Oscar.
I went to the wall and it clicked even more. In the past, I'd feel like I was hitting the ball really well, but I couldn't build on it because I'd eventually try to frame the shot w/ the goal of hitting through 3-4 balls in a line rather than deflecting and accelerating.
This isn't a bad shot and has gotten me to 4.0, but I feel that I can hit the ball just as consistent and w/ more spin w/ his method.
Back to the videos of Oscar, I think he may be exaggerating the motion? I initially dismissed it b/c I thought he was just arming the ball over the net...
I have his book now. I think the next level of the club will be "stalking the ball." This again seems odd to me. But on thinking about it, I note that I sometimes hit my best groundies returning a flat serve. If I have enough time to do that then I shouldn't be late on a groundstroke.