The pick value for Appel is $2.9 million. The Pirates can't use that money elsewhere, only on Appel. However, they've saved about $600,000 against their overall pool so far by signing several top-ten draft picks to bonuses that were well below their pick values. They can also go over their total pool by up to five percent without losing picks next year, which gives them approximately $330,000 more.
That's a total of $930,000 they can use to add to Mark Appel's $2.9 million pick value. Or not. They can also choose to spend it all in one place, on someone like Walker Buehler. Or (and this is where the nasty part comes in) they can call Appel right now and offer the entire $3.83 million. If he says no, they can start spending the $930,000 overage in small chunks, kind of like a kidnapper sending fingers and ears to someone he's trying to extract a ransom from.
Looking at Vlad's piece from earlier this week on the signability of other Pirates draft picks, someone like Kevin Ross, who the Pirates took in the eighth round, might require more than the $138,200 pick value to sign. So if Appel won't sign for $3.83 million, the Pirates can sign Ross for, say, $250,000, thereby reducing the amount of money available for Appel's bonus by about $110,000. Then the Pirates can call Appel again and threaten to do exactly the same thing with, say, 15th-rounder Jon Youngblood, or 16th-rounder Max Moroff, or 37th-rounder Jacob Waguespack, thereby reducing the amount of money available for Appel. If he won't sign in the end, again, it's no big deal.
Of course, this doesn't have to sound nasty. In fact, it's just a way for the Pirates to continue to add talent to their system without letting Appel and Scott Boras control them. If Appel is unwilling to sign right now, that's fine. But the Bucs need to continue to add talent to their system. As Huntington put it a couple weeks ago:
"With (picks) 1 through 10, every dollar you go over (slot), you’ve got to create a dollar somewhere else," he said. "We’ve been able to create some dollars, so it isn’t taking away from the allotted $2.9 million that’s sitting there for (Appel). If we start chipping away at some guys beyond the 10th round for more than $100,000, then we do start losing money we’ve got available (for Appel). It’s all part of the exercise."
It's all part of the exercise. If Appel would like to sign right now, great. If he wants to sign three weeks from now, the Pirates can tell Boras that there just won't be as much money there for him.