Husbandry is an essential part of breeding. Having males together, with hens to compete over, is often a recipe for such issues.
This is all a normal part of chicken dynamics. The one barred Rock is the oldest and biggest, by the sounds of it. He also appears to be the Alpha or male that believes himself to be in charge. As the largest and oldest? Why wouldn't he?
These huge, true bred Plymouth Rocks are cockerels and they will grow to be enormous cockbirds, with heads almost to my 29" inseam waist height and they'll weigh upwards of 11 pounds with ease.
Having all your males and females in a single confined, coop/run "flock" is simply not going to work. You can run females in larger groups, but too many males in a group will eventually result in a fights for domination. If you ate this oldest male for dinner tomorrow, you'd still be postponing the inevitable with the other two males as they too reach "the age".