Collingwood in Nelson's place at Trafalgar

What changes if Collingwood replaces Villeneuve at Trafalgar?

Nelson would have a harder fight, but Collingwood would still command crews that lacked the ship-handling proficiency needed to overturn the basic British advantage.

Nelson would face more difficulty if Collingwood replaced Villeneuve, but the French and Spanish fleet would still suffer from the same crew limitations. Collingwood could change decisions at the top without instantly teaching sailors to maneuver and fight unfamiliar ships. Trafalgar cannot be explained through admirals alone. Command quality matters, while training and practical seamanship still constrain what even a stronger commander can accomplish.