Battlecruisers, carriers, and sea-control task groups

What would have to change for battlecruisers to become more important than battleships?

They would evolve toward fast battleships and gain greater value in carrier-backed task groups once a battle fleet had secured command of the sea.

The battle fleet first has to secure command of the sea by containing the enemy's main force. Once that condition exists, fast capital ships become valuable for commerce denial, trade protection and wide-ocean response. Converted Admiral-class carriers could operate with Hood, Renown and Repulse as three fast strike groups, while slower carriers worked with the battle fleet. A larger Fleet Air Arm would add reconnaissance and striking reach, although 1930s engine and endurance requirements might still favor powerful biplanes for long-range carrier work. Battlecruisers also mattered before combat because prospective enemies had to account for their speed and reach in their own plans.