Gerald Green’s windmill alley-oop is the clip everyone knows. It may not be the highest he ever got. His practice height checks look even higher to me, and those jumps are why I put his maximum around 45 to 46 inches.
The windmill and the practice jumps
The video starts with Green at six-foot-seven without shoes and adds about an inch for the pair he is playing in. At roughly six-foot-eight on court, he needs about 40 inches for his head to meet a ten-foot rim. His famous windmill gets his head a few inches over it. In the practice clip I use, the head position looks higher again. That is the difference between a spectacular dunk and the jump that may be most useful for estimating his maximum.
A height check has a catch: a player can lean, tuck or change body position while reaching, so head height in one frame is not a laboratory reading of center-of-mass rise. The camera matters too. Still, the clip is useful because Green has room to attack the jump and does not have to turn the attempt into a windmill. I use the windmill as a reality check and the best practice jump as the upper end, rather than treating either as a perfect measurement.
Does he jump higher in games?
I asked Gerald that question directly. His answer had me laughing: he said he could pretty much get out of bed and jump the same. Some other players told me they needed game adrenaline; others wanted the space of a contest or practice. You can hear the different answers in the games versus warmups video.
The windmill gives us a high game jump; the practice check is my upper-end reference. Together they point me to 45 or 46 inches, with more uncertainty than a properly measured jump would have. The NBA estimates table keeps that range next to the actual clip.