Incorrect! Let's do a direct comparison.
Frog: 2 quanta, 5 DPT.
Scorpion: 3 quanta, 2 DPT + 1 PPT.
A direct comparison.
Turn 1: Play two pillars. Frogs get out, Scorpions don't. Frog: 5 - Scorpion: 0
Turn 2: Scorpion gets played. Frog: 10 - Scorpion: 2, 1 poison
Turn 3: Frog: 15 - Scorpion: 5, 2 poison
Turn 4: Frog: 20 - Scorpion: 9, 3 poison
Turn 5: Frog: 25 - Scorpion: 14, 4 poison
Turn 6: Frog: 30 - Scorpion: 20, 5 poison
Turn 7: Frog: 35 - Scorpion: 27, 6 poison
Turn 8: Frog: 40 - Scorpion: 35, 7 poison
Turn 9: Frog: 45 - Scorpion: 44, 8 poison
Turn 10: Frog: 50 - Scorpion: 54, 9 poison.
Even if you get them both out at the same time, frogs are still only equal to scorpions damage wise after 7 turns, whereas an effective rush deck only takes 6-5. The extra quanta makes rushing frogs way easier, and almost any shield will stop scorpions in their tracks. Scorpion is underpowered compared to every life creature. Cockatrice, for the same cost, are impervious to most control and are a better pick.
And lets take a look at the other scorpions.
Turn 1: Scorpion: 2, 1 poison - Death Stalker: needs a buff.
Turn 2: Scorpion: 5, 2 poison - Death Stalker: 2, 2 poison (eclipse)
Turn 3: Scorpion: 9, 3 poison - Death Stalker: 6, 4 poison
Turn 3: Scorpion: 14, 4 poison - Death Stalker: 12, 6 poison
Turn 4: Scorpion: 20, 5 poison - Death Stalker: 20, 8 poison
Turn 5: Scorpion: 27, 6 poison - Death Stalker: 30, 10 poison
Turn 6: Scorpion: 35, 7 poison - Death Stalker: 42, 12 poison
Turn 7: Scorpion: 44, 8 poison - Death Stalker: 56, 14 poison
Turn 8: Scorpion: 54, 9 poison - Death Stalker: 72, 16 poison
And after a single eclipse, additional Death Stalkers are easy to play. Even without Scorpion's card advantage, Death stalker is better than it within 6 turns. If it gets a 1 damage buff, it's better by turn three. Scorpion deserves a buff.
Turn 1: Scorpion: 2, 1 poison - Death Stalker: 1 - 2 poison
Turn 2: Scorpion: 5, 2 poison - Death Stalker: 4 - 4 poison
Turn 3: Scorpion: 9, 3 poison - Death Stalker: 9 - 6 poison