"(they would be lucky to get replacement level performance from Kozma)"
Time will tell but I think they will be lucky to replacement level performance from Peralta as well. I'm guessing he will hit .250 with 10 HR's and a .650 OPS in 2014. By 2016 he will be worthless as a SS and at best be an average backup 1B/DH. You can cite all the defensive metrics you want, he will give up way more hits than an average SS. If he was a 1B or LF maybe you accept the poor defense and hope he repeats his near career year (at age 31-32) but at SS it's not worth it. I agree giving up a 1st for Drew would be too much but there are some trade possibilities out there, and they would not necessarily have to give up Miller or Taveras either.
The PEDS are just an added negative, if he gets caught again the deal will be a bust, and I don't buy the "other than that one mistake he is a great guy" argument. Mozeliak said “In his case, he admitted what he did, he took responsibility for it". No, not really. Here is what Peralta said last offseason when the first rumors came out - "I have never used performance-enhancing drugs. Period. Anybody who says otherwise is lying." I have never met the guy but he cheated, lied about it for as long as possible, then finally confessed when he had no other choice.
If he was in his teens or low twenties I would be a little more forgiving but he was 30 when he cheated. I guess he is slightly less of a douche than AROD. Put that on your gravestone Jhonny - "He was not quite the douchebag that AROD was".