Moveset is more important than IVs, and Confusion is the better moveset, it has the fastest time to kill against most raid bosses. Only Bullet Seed against Rhydon is faster due to the double grass weakness.
If you look at IV as a percentage then yes, they are lower, but when you look at them in practice, they don't make a significant difference.
14 vs 15 attack, if they had the same moveset would only be a difference of 1 power up to reach a quick move breakpoint, and for charge move it's probably only 1 or 2 extra damage on a Solar Beam.
Same with defence, one extra power up to reduce a raid boss' quick move damage by 1, and reducing it's special damage by 0 or 1 point.
A difference of 2 stamina IV is only a difference of 1 HP at level 30 and 2 HP at 39.