I think it would balance better if the swimmer and runner swapped places
Think its meant to be in Triathlon order...
Its the location of the swimmer that doesn't quite work for me either although understand why they are in that order. Oh and shoes on the swimmer!
I think if the swimmers dive were facing the camera, it would give a constant rotation to the subjects directions and improve the composition problem. Going from Across the frame to coming out of the picture and back to across the frame is quite jarring.
The only thing bothering me Is
the swimmers head up the cyclists back end . I think it would balance better if the swimmer and runner swapped places
I think it would look better as 3 separate images presented as a triptych.