Well for one Hoskins has only hit above .250 in his career once and that was at .259 so the .260-.270 is not going to happen. He will be closer to .215 than he will ever be to .260 or above. If Black hits .290 with 15 bombs that is actually more valuable as he probably hits some more doubles than Hoskins does. If you can get .290 with 15 HR's with Black then why pay Hoskins? If Black can even get to 1/3 of the production that Hoskins does then Hoskins shouldn't be making $16mm+ a season he should be making closer to what Santana does.
Unless Hoskins signs for $12mm or less per year which he won't then it is not worth signing Hoskins. Would you pay $300k for a regular Mustang or $300k for Lamborghini Huracan? Basically Hoskins is that $300k regular Mustang in this comparison. The price per performance is not worth it when you are paying a premium.