D&D 5E Monster Math: CR1 vs CR½ - Quantifying the differences

[Savage Wombat]

The Kuo-Toa Whip is CR 1 and has 65 HP. And it's a spellcaster. Does this make sense?

 

[surfarcher]

The Kuo-Toa Whip is CR 1 and has 65 HP. And it's a spellcaster. Does this make sense?

It's spells are primarily defensive and it's traits also boost defense. It doesn't have spike damage capable of taking down a single level 1 PC in one hit. It doesn't get significant Advantage on attack either. I peg it as towards the upper end of CR1.