I think he means that each spin, 5 cards are picked. Lets say you beat an FG, you get 3 spins. 5 cards are picked for each of the 3 spins. So effectively, you could have 15 different cards on there. Thats the way I interpret it. I guess more cards means less chance of getting a certain one.
Allowing for Ashebrethafe's correction of only 4 out of 5 cards appearing in each spin, this still doesn't sound right.
Let's say you win a T50 match against an opponent with 30 cards (so three spins). Have you ever noticed that if cards like Boneyard pop up in one spin, it will probably make an appearance in the second or third as well? You know there can't be more than 2 of those in the deck. Assume 12 pillars.
So you're saying it picked 5 cards out of 18 (not counting pillars), displayed 4, and Boneyard was one. Then it picks 5 NEW cards, displays 4, and picks Boneyard AGAIN? And possibly a third time?
One the one hand, more than 5 cards appear in spins. On the other hand, the SAME cards appear in different spins enough that it doesn't seem that 5 new cards are pulled for each individual spin.