Dejan Kovacevic of the Trib has an interview with Scott Boras, who happens to represent Pirates No. 8 overall pick Mark Appel. Kovacevic characterizes both the Pirates and Boras as having their backs "to the wall."
I wrote a long response at Bucs Dugout, but essentially, I think the only party here with any leverage is the Pirates, and the Bucs aren't "to the wall" here in any way. If the Pirates don't sign Appel, they get the No. 9 overall pick in next year's draft. And as annoying as the new draft rules may be for the Pirates, they do place fairly severe limitations on what the Pirates can spend on him -- and, significantly, on what other teams might be able to spend on him if he were to reenter the draft next year as a college senior. There's no reason whatsoever for the Pirates to panic. If they have to let him go and take the No. 9 overall pick next year in what's likely to be a better draft than this year's, eh, no big deal.