Largest Lead Prop Question

[BRDSR]

Considered putting this in chatter, but it doesn't seem quite so newbieish to be required to go there. Mods please move it if you feel otherwise.

I'm seeing a prop bet at my book that reads: "Lakers vs. Suns - Over/Under Largest Lead of the Game" The o/u is 19.5 (-115).

Am I correct in believing that if I took the over, one team or the other would need to amass a 20-point lead at some point in the game? If I took the under, neither team could ever lead by 20 at any point in the game?

If I have this right, it seems like this has "5-unit bet" written all over it. Lakers are getting 9.5 points, and I'm fairly certain I'll take them against the spread.

So, here's my question. Assuming +9.5 is actually the correct line in this game, does it seem unlikely to you that the Lakers will be down 10 more points than that at any point in the game? If, on average, they did get down by 20+ and, on average, they lost by 9.5 points, that means it would have to be likely that they would go on a +10 point run at some point in the game. That just doesn't seem likely to me, making me believe that one of the lines is wrong. As I already said, I think the spread is wrong and should favor LA a little more.

Does this seem like as easy a bet to anyone else as it does to me?