Thinking of Dustin Ackley as a member of the "prospects" species.
Can't lump him with "prospects" like Chavez, Mangini, or whoever.  But that's what people do.

The catch? He'll probably cost you at least -- and I'm saying at least -- two of the Big Three prospects in Dustin Ackley, Justin Smoak and Michael Pineda.

Meaning that Upton might well cost you all three of those guys.
Again, the fatal flaw in this logic is to lump Ackley and Smoak as "prospects."  They are not.  False premise = invalid conclusion.
Baker is thinking that Ackley is roughly comparable to, say, Jeff Clement, Phillippe Aumont, or Brandon Morrow, simply because he was drafted in a similar spot.  Which is like saying that Strasburg and Lincecum were comparable in value to other top-pitchers-in-the-draft.
The very moment that Ackley and Smoak begin hitting well, at all, in the bigs, they are each worth more than Justin Upton.
....................
Fortunately, Geoff's reasoning on Zduriencik is simply that Z is smart enough to know that proven players are worth more than prospects.  Guarantee you that Z would not back this logic.

"Jose Lopez was a 25-homer second baseman in 2009. How many of you thought he was untouchable? Ackley looks like he'll be a superior OBP guy compared to Lopez, but who really knows? Remember, Ackley is still a prospect. He hasn't played in the big leagues where Lopez has proven himself there at some level.
Bottom line? Ackley as he looks right now should not halt an Upton deal. You can find line drive hitting second basemen to fill in for a couple of years until you figure out what else you're going to do. "
Ugh.  This is...um...Ackley will have to get hit by a truck to only be as good as Jose Lopez was in this park.  A line-drive hitting 2B without walks may not be untouchable, but a hundred walks a year from the middle-infield is so special as to be a singularity that must be put to use.
Still, I could see today's trade for Juan Miranda that the D-Backs did being a way to compensate us for losing our 1B.  The Yankees aren't gonna trade with us immediately after we "screwed them over" on the Lee deal.
So AZ goes and gets a 1B for pretty cheap that they can swing our way to compensate us for losing our projected 2011 starter at the position in Smoak.  Miranda's line would be something like what we wanted Kotchman and Carp to do.  Upton + Miranda for Pineda + Smoak + buncha relievers would be understandable.
I'd be less pleased with that deal, but sometimes you don't get a choice.  I still don't think it would take what Baker thinks it will take.  Maybe Towers refuses to budge without 2 bonafide top-20 talent blue-chippers ready to start in the bigs tomorrow, as well as ML-ready bullpenners, but Saunders isn't nothing either.
I dunno, I just think we've got enough in the system to get it done without moving Smoak.  Pineda is better than Drabek, the centerpiece of the Halladay trade.  Michael Taylor in that deal was a well-thought-of prospect, but no better than Saunders (Saunders was #30 on the BA prospect list pre-2010, Taylor was #26.  Saunders moved on to the bigs, Taylor regressed in AAA in 2010, so whose stock is higher now?).  D'Arnaud was a catcher who was years away when the deal was made.  He's a Chavez/Seager level prospect, maaaybe.
Pineda, Saunders or Gutierrez, two relievers and one of the High-Desert crew should be as good or better than anything that's being offered.  I don't move Smoak or Franklin unless Stephen Drew is involved.  I don't move Ackley at all.
And I could live with that first package.
~G

I dunno, I just think we've got enough in the system to get it done without moving Smoak.

And if we can't, I'm blinkin' happy to live without Alfonso Soriano in Safeco.  In precisely three months (baseball time) EVERY fan will be thrilled we didn't give up Justin Smoak for Justin Upton.
Pineda is better than Drabek, the centerpiece of the Halladay trade.

Word, there too.
Pineda and other goodies we have are plenty 'nuff.  But if they don't want to trade, fine.  There are other trade targets.  Somebody will give up a hitter for Pineda, Gutierrez, and four other prospects.

"Jose Lopez was a 25-homer second baseman in 2009. How many of you thought he was untouchable? Ackley looks like he'll be a superior OBP guy compared to Lopez, but who really knows? Remember, Ackley is still a prospect.

I love Geoff ... but IMHO Dustin Ackley is a litmus test, the way that Tim Lincecum was, the way that Ichiro was.
Ichiro was regarded a #4 outfielder by, um, Mike Hargrove.  If Ty Cobb were playing AAA baseball, thre are folks (not talking Geoff here) who wouldn't recognize him.
I know guys who can tell you, in 5 minutes on a practice field, who the Michael Jordans and Peyton Mannings and Ken Griffey Jr's -- and Dustin Ackleys -- are.

If we can add Alfonso Soriano in LF, fine.  I'd like him, sure.  But why would I trade (what I expect to be shortly) an .800-.850 OPS 1B for an .850ish LF, while giving up a raft of talent and paying more money?
Yes, this Soriano could turn into Juan Gonzalez.  Smoak doesn't top out in the low-to-mid .800s with his potential either.
I just don't move Smoak to do this.  As I've said, I would go try to get Colby Rasmus with the Pineda + Gutierrez + relievers package if the D-Backs don't want it.  That would give us that production from a center fielder, leaving extra offensive slots open for bats at lesser-glove positions.
I'd be happy to add Upton - just not at a Pineda + Smoak + a bunch of others cost.  Baker intimates that's just the cost of doing business; getting real-world production immediately costs talent, and if you pay it in prospects, fine. 
I'm with you:  some players are prospects (Clement, Chavez, Robles) and some are production-in-waiting.  Ackley is production-in-waiting.  All we have to do is put him to work and even his downside is better than any 2B we could reasonably add another way.
Smoak isn't quite on that level for me yet, but he really did start to impress me in Tacoma and at the end of the season.  If he was just Tino Martinez that would still have great value to our next half-decade, and that's not his top-end by any means.
~G

Would chase a Pineda/Rasmus deal a million times before I'd chase a Smoak/Upton deal...
Yes, this Soriano could turn into Juan Gonzalez.  Smoak doesn't top out in the low-to-mid .800s with his potential either.

+1

Ackley I hold onto. The eye is too great, even if the defense dissapoints. High probable impact player, even though he probably won't be as good as Upton. No point in trading him though since its a lateral move and Ackley fits a bigger need.
Smoak? I absolutely trade him in a package for Upton. Upton put up a 899 OPS as 22 year old in the bigs and is the most talented prospects since Josh Hamilton.
Pineda AND Smoak? This is a little much. I'd do either guy + several great secondary pieces, both is pushing it.

Towers, well aware of the no-trade, then proceeded to negotiate Ackley in the press :- )

...but more to the point...Baker has several deep personal biases that make no sense in this particular context. He believes (probably rightfully so) that it's always better to trade for an established star you're certain you'll be happy with than to hope two prospects work out. He believes (and again, I find no fault in this general logic) that winning clubs don't hem and haw about fixing their glaring weaknesses with established big league (TM) talent, and he believes that the road to winning in paved with bravery in trade talks...being willing to give up something good to get something good.
The problem here is that Ackley isn't a prospect...he's a freak of nature, Upton isn't a sure-thing superstar and the Mariners aren't close enough to contention to gamble big on the prospects they've finally managed to assemble in the high minors. Let's not forget, as well, that we're operating on a limited budget (whether you think we should or not) and Ackley costs ne3xt to nothing while Upton costs 50 million the next five years.