Why cutting a first-rate down rarely produced a superior third-rate

Did navies razee first- or second-rate ships to create unusually powerful third-rates?

Occasionally ships were cut down, but the result lacked the dramatic structural and sailing advantages gained by converting a ship of the line into a frigate, so a purpose-built third-rate was usually better.

A first-rate and a purpose-built third-rate already used broadly comparable heavy hull framing, so cutting away a deck did not confer the protective advantage that a razee frigate gained over ordinary frigates. The reduced ship also received less relative benefit in sail area, mast support, and rig than a ship-of-the-line-to-frigate conversion. Using Victory as the example, combining the surviving lower batteries and lighter upper works would leave something closer to a 64-gun ship than a strong 74. First-rates and three-decked second-rates were also scarce, making such conversions an unattractive use of valuable capital hulls.