A cursory glance at the Cubs' roster tells you a lot about the makeup of this team. They look be to a middling rotation, a middling bullpen, and a bottom-third offense. That's a good enough team to win 73-75 games (which would be a dozen or so win improvement); not the worst team in baseball, but not a good one either. I think that even the most optimistic of us (like a dmick-type Cubs fan) realizes that at some point in the season, the Cubs are going to sell off as many assets that make sense as possible. Who could those assets be?
Category #1: Overpriced, but Productive
This is where Carlos Marmol and Alfonso Soriano fall. Marmol makes $9.8 million, which is pretty ridiculous and one of the remaining artifacts of the Hendry Era. I didn't hate the idea at the time, and I can't pretend to know what payroll limitations Hendry was under, but here we are nonetheless. Marmol is a great bet to be traded, and it's not unlikely to happen before the season starts either. The Cubs will likely eat a fair bit of it and get a lottery ticket arm in return.
Alfonso Soriano is the other stamp on the Hendry Era that lives on. Soriano has, in fairness, been about as good as advertised during his tenure with the Cubs; his contract gave many fans an unfair expectation of his skillset. Before the Cubs, his OPS+ was 115, and on the Cubs it was 113. He's due for a steep decline in the near future, but the Cubs could get a mid-15 prospect in a team's system if they ate enough money (and all signs point to a willingness to take on lots of salary).
Category #2: Expiring Contracts
Nate Schierholtz was the biggest offensive signing of the season, which tells you exactly how competitive the Cubs think they are this season. He was brought into platoon at RF with Scott Hairston (our other big "get"), but he doesn't actually have an advantage either way: he's definitionally mediocre against both hands. He does have a higher BABIP against LHP (.343 to .300) and a lower OPS against them also (.732 to .708), so theoretically you expect some erosion in his skills against lefties. However, he's just average against righties anyways, so his value is strictly just injury-replacement at the deadline. Market and injuries will 100% define his value in a trade, but I can see him being as valuable as a 4-7 org guy in the best circumstances.
Scott Feldman is another one-year "prove it" deal. He's not the greatest pitcher in the world, but serviceable back-end types moving to the NL can catch some magic now and again. In the best case, he's slightly less useful than Paul Maholm in a trade (he has no option year), but I'd imagine that he'll reach that level of value safely. He's going to get every chance to start this year, and his peripherals have improved even if his standard stats haven't. I wouldn't be at all surprised if the Feldman signing turns out to be the best move Hoyer made this year.
Scott Baker might not throw another pitch for the Cubs. If that's the case, the Cubs effectively burned 5.5 million. However, it's far from certain that Scott #2 is cooked. He was quietly phenomenal in 2011 (of course, that's a TJS and 2 years ago), and his peripherals indicate tons of talent (lots of Ks, not many walks), and I'm cautiously optimistic about what that means if he can get on the mound. It's very difficult to imagine what his trade value might be, so I'm not going to speculate on it.
Everything I said about Baker I can just repeat for Garza. At this point, I think the Cubs are probably better served trying to extend Matt, because it's hard to envision getting anything approaching "fair value" for him.
Shawn Camp was the MVP of the Cubs last year, according to Dale Sveum. He parlayed that honor into a huge 1.35 million contract this year. For comparison, the Cubs paid Dioner Navarro 1.75 million this year. Camp could net a live arm in a trade with a repeat performance of 2012. Anything more than that is a bonus.
Category #3: Talented and Cost-Controlled
David DeJesus is a reasonably-priced, reasonably-good CF/RF. He's due to make 4.25 million this year, and 6.5 next year. That's a pretty valuable trade chip. Not only is he likely to be among the better deadline options out there, he's actually an upgrade for plenty of teams that might not even have an injury. DeJesus could garner a decent prospect if the right situation presents itself, and the Cubs will almost certaintly extract some value from his trade.
Kyuji Fujikawa is a huge question mark, but the elder Japanese closer signed for 4 and 5.5, which means he could be very attractive in a trade at the deadline. Japanese pitchers have a tendency to overperform in the first year, which could also be to the Cubs' benefit. I'm not sold on Fujikawa being traded at all (for reasons even I don't know), but it's feasible to envision a scenario in which it does happen.
Sure, you can throw Carlos Villanueva in here. He's making 5 and 5, which is reasonable. I don't think he's going to be anything special for the Cubs, but hey, if you need a warm body to soak up innings…
Scott Hairston is a lefty-killer. Pieces like this get traded for unexpected returns every so often, so don't sleep on him. For that to work, though, he's got to OBP over .299. Come on, Hairston. I know you can do it.
Category #4: "Foundational" Pieces
I'm not sold on Darwin Barney being anything more than an excellent backup MIF in the future (I imagine many front offices share my view). There just isn't enough value to a glove that's attached to a bat that will optimistically flirt with the .300 wOBA line. The Cubs likely value defense pretty highly, and another team might share that view. Depending on the scenario (perhaps a high BABIP plus a modest progression in power), the Cubs might be able to flip Barney for some real prospects (and his great contact skills ensure that he'll make good use of a BABIP swing in his favor). The Cubs have flirted with the idea that Barney is a definitive part of the future. All it takes is one sucker at the table to change that, though.
Jeff Samardzija is about as difficult a pitcher to project as you're going to find in baseball this year. He's got the tools to be a legitimate #2 (he throws gas, has a great fastball, and a plus splitter). He's also got a tendency to leave balls high in the zone, where they get CRUSHED. Samardzija isn't a great extension candidate, but another team might not see it that way. He's cost-controlled for the next few years with a skillset scouts can dream on. In a trade, Shark could net a huge prospect. If James Shields is worth Wil Myers plus, Jeff Samardzija is worth more or less the same amount – but only if he continues at his 2012 pace. I think there is a real shot that Shark gets traded for a HUGE package this year if extension talks prove less than fruitful, and the Cubs will definitely be looking for impact arms in return.
Everyone else on the Cubs roster is either a "foundational cornerstone" that will require an unlikely offer to move (Castro or Rizzo), pieces that just don't make sense to trade (Castillo, Russell) or are just flotsam/jetsam that won't get much in return (Navarro, Clevenger, Valbuena, Stewart).