My counter to that would be Ben Simmons & Melo Ball. Both look/looked like HOFers in practice. My other counter argument would be The Greentree practice reports.
I agree w/ u that the combine often distorts the draft decisions of GMs (see Anthony Richardson), but by far & large most decisions are based upon game production. The combine simply either verify or give GMs a quick assessment to revisit game film to see if a player’s potential is A+, undervalued, or overvalued.
Production will always be king, but of course a GM is going to take a chance on a guy who’s running a 4.2-.3, 40 in vert., benching 225 20+ times, &/or can launch a ball 70+ yards with decent production. They do same thing when it comes to recruiting at the collegiate level, & what determines at blue chip from a 3* or lower.