He was one of the great draftsmen of his time. His figures have weight, fluidity and emotion.
One thing that's not evident is the amount of preparation he put into his painting. I don't simply mean his then-controversial experimentation with photography and use of nude models for figure study (can you imagine that as controversial in art study?).
He planned out his work thoroughly beforehand.
Perspective study, including vanishing point.
Separate perspective study for wall.
In the painting we're working with ("John Biglin in a Single Scull" -not the one pictured here) he went so far as to do a study of the piece -in oils -before executing his "final" watercolor.
Great work comes from hard work.