quick theorycraft for
A 5/5 body is worth about {4} in today's meta, then it's summon a random minion based on hand size. For big spell mage constantly running close to 7-9 cards that's a {4} and a {7}-{9}
Assuming i have 9 other cards, here's a
link to cards this might draw currently.
In my current big spell mage deck:
Win condition: Hadronox is a win condition for me, Dragonhatcher can be if i run bone drake or another big dragon which i have at certain points, rounding out the 9's we have
Amazing: Gruul, King Krush, Malygos, Obsidian Statue, Sleepy Dragon, Ysera, Void Lord
Good/big bodies: Alex, Baku, Giant Mastodon, King Mosh, Nozdormu, Onyxia
Meh: Cenarius, Shudderwock, Lord Jaraxxus, Ozruk, Master Oakheart
Weak: Dragoncaller Alanna
So something like 50% are amazing+, and like 70%ish are at least good+ big bodies like Baku or King Mosh.