Can we not massage the figures to indicate that the success that a signing of that caliber would bring >= the depreciation in their value?
Sure, let's toss around some figures.
Say you're looking at two players:
Player A is a veteran DP, 29 years old, coming to us from a midtable Serie A side. His transfer fee is $7m and his annual wage is $2m. He's looking at a 3-year contract.
Player B is a young DP, 20 years old, coming from Uruguay. He costs $4m and his annual wage is $1m. He'd also come on a 3-year contract.
Player A is a known quantity. Imagine, just to simplify this hypo, that soccer has a workable Wins Above Replacement stat. You've crunched the numbers and expect that his performance curve looks something like a 25% chance of 4 WAR per season, 50% 5 WAR, 25% 6 WAR, for an average of 5 WAR per season or 15 WAR over the 3 years of his deal. At $13m over the life of his contract, you're paying $0.9m per win.
Player B is more of a gamble. You expect he'll get better as time goes on, but your projections for him look something like 10% 0 WAR, 20% 1, 25% 2, 20% 3, 15% 4, 10% 5, for an average of 2.4 WAR per season or 7.2 WAR over 3 years. At $7m over the life of his contract, that's $1.0m per win.
So far Player A looks like the clear winner. But now you start doing some math on your exit options. Let's say there's a 10% chance you sell on your 32-year-old DP at $2m, 30% you get $1m, and 60% you get nothing. That offsets his expected cost by $0.5m, so you figure you're paying $12.5m for those 15 WAR, or $0.8m per win.
But Player B's already had some interest from Europe. By age 23, after a few solid seasons developing in MLS, you expect there's a 20% chance you've doubled his fee to $8m, a 50% chance you can sell him on at a break-even $4m, and a 30% chance he's stagnated and is effectively worthless. You've offset his expected cost by $3.6m, bringing his rate down to $3.4m for 7.2 WAR, or $0.5m per win.
Now your Uruguayan kid's looking like a real bargain, even factoring in the uncertainty. You've left 7.8 wins over 3 seasons on the table, but you've also got $8.6m left in the bank. Even if you purchased those remaining wins at Player A's sure-thing vet rate, they'd cost you $6.5m, leaving you a $2.1m surplus. So go with Player B, right?
Maybe. Like you pointed out, there are still some complicating factors beyond the uncertainty around performance and transfer fees. One big one is the salary cap, which makes it hard to spend that extra $6.5m over 3 years to make up the projected WAR gap. Here the Young DP rule helps, since under the current roster rules you'd get an extra $1.0m in cap space over 3 years if you went with Player B. But you'd still really have to stretch your allocation money to find room to spend another $5.5m to balance out the WAR.
The part that's harder to put a number on is your concern about support. Is Player A going to put more butts in seats because he's a better, more proven player? Or will people turn out to see Player B to say they knew him when? And what's the ballpark range for a single player's drawing power in dollars? If we use Maxi and Medina as the closest analogues on our roster right now, it seems to me people care more about Maxi, but that could change if Medina grows over the next year or two, and neither's much of a draw compared to Villa anyway.
Here's my thinking on all this: Player A and Player B are both solid options. Maxi and Ruidíaz are good, Medina and Diego Rossi are good, and MLS could use more signings like all of these guys. Since we've already got one Player B type on the roster, I might be inclined to take the higher WAR guy. On the other hand, it's risky to put all your eggs, etc. etc., and maybe you want to spread the WAR around when Dome does a rebuild. Plus it's super fun to root for kids and watch them grow and maybe see them become that midtable Serie A player in the future. I guess I'm good with whatever. But given what we've seen from NYCFC lately, I think they'd want to try to snag the bonus $2.1m that comes with Player B in our made up scenario. Just seems like where we're headed.
So anyway, yeah, I wouldn't be surprised to see us replace Villa with a Young DP.