I think the stats of Jabberwock should be high. Jabberwocks are very large.
From the poem, here's what we know about Jabberwocks:
"Long time the manxome foe he sought
-- so rested he by the Tumtum tree,
and stood awhile in thought.
And, as in uffish thought he stood,
the Jabberwock, with eyes of flame,
came whiffling through the tulgey wood,
and burbled as it came!"
So it seems that if you take action seeking the Jabberwock, it remains hidden, but when you pause to think it reveals itself.
So how about this:
Initial stats on Jabberwock are 0/15 costing 5
The card text says:
Dies if lobotomized. Manxome: If your opponent did not play a card last turn, Jabberwock becomes 15/1 until end of turn.