Chavez is in my top-3 tradable minor leaguers - guys that have worth that I would give up now in order to improve the club because I don't think they'll ever be a contributing part of the big league roster.
His stock is (or should be) through the roof for all the reasons previously outlined: great work ethic, #1 hitting prospect in Blue Jays per a few different outlets BEFORE he took it to eleven in the Cal League for us, improving batting eye, cannon from the outfield, scads of power, et al.
And yes, AS HE HAS BEEN, he is unlikely to have major success in the bigs. His eye wasn't good enough until the 2nd half of this year to compensate for his massive K totals, and those totals were too massive for his number of ABs to boot. IF his work with the batting coach in High Desert helped him turn a corner, great. He's got a shot to make the bigs and be a minor star.
I still trade that guy.
But THAT'S the guy you want to be trading (110-130 OPS, corner OFer, top outfield arm, etc). You want to trade a shot at Geoff Jenkins, not just the continually mired Greg Halman or Mike Wilson.
If he hits AA and crashes back to earth with worsening K rates against better breaking balls, etc, then his stock drops, probably irrevocably. We need to pull a Gillies with someone from High Desert. Poythress, Seager or Chavez needs to go. They're riding huge numbers, huge 2nd half numbers, maximization of their skillsets...
I'd pick Chavez to go, though Poythress is a good option too.
We should be able to get a LOT for Chavez + someone like a Robles. You suggested Pineda + Saunders + Chavez for Colby Rasmus on MC. I'd swap Pineda for Robles and then make the call. That would be 3 months of Wash + 1/2 of Morrow + a AAAA player for 4 years minimum of a power LF bat who could move to RF if Ichiro ever stopped playing.
I think it's more likely than you do that Chavez gets it right and can make a positive impact on a ML roster someday, but I don't bet those odds. I'd trade him just like you would, especially as a package for an impact player.
~G