Observations from arbing/whoring

[TheOffice]

I'm mostly a poker guy, but have been betting sports for much longer. This has been mainly soccer though, so please excuse my dumbness on American sports.

So I've been trying to whore books just for the heck of it (time invested in poker would've yielded 10x as much at least) and stumbled across the following a phenomenon that's freaking me out.

Whenever I find an arb line, mostly

NBA +110 on matchbook/pinnacle vs. -110 on random sportsbook,

to fulfill wagering requirements, the -110 line seems to be winning an awful lot more as I'm reloading pinnacle and matchbook like a madman which I personally hate, as busting whored accounts would be much nicer.

Just variance (~80 games) or should I be putting more thought into this? This is driving me nuts.