I think that player with the same skills as yours AND with good SB cost that much more, because they are simply THAT much better. You can't realy compare it, but I'm sure that if you square them off against each other, your player will always loose the battle to a more multiskilled player... Maybe others might think otherwise, but that is how I see it.
Also at those high levels of skills, sublevels indeed start to weight hard on the wage. It's very well possible your player is prety low on all of his skills, while the other players you saw are high in their skills, and have the additional SB to add to their wage...
I'm not very sure, but I think you base your 'facts' on a little to few information. I'm positive SB doesn't weigh any harder then any other skill on the wages. Ofcourse a center will ask more wage for shotblocking then a PG would, but so will a PG ask a lot more wage for his handling then the center will.
So far I didn't see any info about SB being excessively expensive on wage, not even with your examples.
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