In this case yes for half your original bet....Take a long hard look at the closing number if it gets as high as 8 you will have gone through some key numbers. When these lines rise rapidly like this (in this case b/c the starting QB is out) the Fav can't beat the closing number and everyone who waited gets baked.
From your perspective you can't loose..
If BC covers the closing number - Oh well you still win half your original
If BC covers the -4 but the not closer you look like a genius
If BC Fails to cover the -4 you feel sharp for buying back half your bet.
Just one guys opinion
GL POwerz