After one season his value was zero? A bad start may have soured the organization, but unless he blew out his arm the basic talent was still there.
Nor had McWilliams done more than show faint flashes.
And they're being traded for 16 year olds in effect.
Point is in all cases we're talking limited value, they weren't actually trading for the allocation to sign Ortiz, they were trading for additional money to take a number of very low "ranked" LA players.
The Phillies allocation is probably enough to sign 1 top ten guy, maybe one other in the top 30, they'd be trading for allocations to buy more Sal specials. Which is good, but means you don't want to be trading good prospects so you can sign another 5-10 LA "scrubs" (because the best specials were probably already locked up by the team, I'm sure they have a list and check it twice).
On the other hand, because the trade value of these allocations are so low, teams will refuse to trade out of pique, to keep their options open, or in the hope they can garner something better by being stubborn.
I expect the Phillies to be buyers when it comes to allocations because they've committed a lot to scouting in LA, and can make better use of allocations than many teams (it's not just the money spent on allocations, but the money you have to spend on your scouting network to find players worth spending money on - it's a lot easier to scout the top 50 than the next 500).