as to what Shap does that results in this: first is his aggressive play style. He really goes for his shots, from all areas of the court. This leads to increased shanks when he’s on the defensive and pressed for time in particular. Second I’d wager that he has a smaller zone of good contact relative to other players. If you extend into the stroke you’ll tend to have a larger zone where your shot connects well. Shaps seems to have reduced that area for more acceleration. The trade off is easier penetration/power/spin but more difficult timing. I’m not 100% on the second one, it’s how it seems to me from some match play and his practice sessions, but the first one is a huge factor for sure.
The lab results are bad for such real-play speculations because they assume a constant incoming ball, no requirements for movement on the player’s side, and basically identical stroke form in kind (the only thing that differs is speed of the stroke, angle of the racquet face, and its trajectory moving into the shot, but there are many more ways to view a shot that are important).