ESPN Boston's Gordon Edes tweets that the Theo Epstein compensation deal is "close" to being finalized, with the Red Sox receiving "one quality minor leaguer" from the Cubs. The identity of the prospect is not known, but that's something we can guess about.
If Bud Selig wants to punish the Cubs so that teams are more reluctant in the future to poach executives from other front offices while they are still under contract, then we're talking about Brett Jackson. But Selig likely isn't going to punish the Cubs to that extent, and the Cubs probably didn't include their top prospect on the list of acceptable compensation, so let's just agree now that it's probably not Brett Jackson.
The Cubs have other prospects, though, the kind that would fit into Boston's system of depth. Boston and the Cubs are in the same position as far as a lack of high-end prospects go, but the Cubs have quite a few mid-level prospects who should end up with major league careers.
Baseball Prospectus's Kevin Goldstein ranked the top 20 prospects in the Cubs system back in November. Unsurprisingly, Jackson was first, but we agreed to forget about him. Shortstop Javier Baez came second, as the Cubs lone four-star prospect -- his ETA is 2015, and, like Jackson, the Cubs might not have included such a high-ceiling prospect on their acceptable compensation list. (We don't know this, of course, but for the sake of being realistic, let's run with that view.)
Goldstein then ranks seven three-star prospects in the Cubs' system:
3. Welington Castillo, C
4. Dillon Maples, RHP
5. Matt Szczur, OF
6. Josh Vitters, 3B
7. Jeimer Candelario, 3B
8. Trey McNutt, RHP
9. Marco Hernandez, SS
That seems like a fair place to search for the "quality" mentioned in Edes' tweet. A three-star caliber prospect would work as fair compensation for the Red Sox, in that they get someone who should actually contribute with the Red Sox (or be useful as trade bait at another time), and, while the Cubs and their system would miss the player in question, they still got off the hook easy in a relative sense.
Welington Castillo is a Triple-A catcher; with Ryan Lavarnway around, it's unlikely that's someone the Red Sox were targeting. Maples was a 2011 draft choice. If this compensation is being viewed as a trade, he's not eligible to be dealt yet. If not, he's a 19-year-old righty with loads of upside. Given he hasn't pitched professionally yet, though, he might not be the target even if he is eligible to be moved.
Matt Szczur will be in his age-22 season in 2012, and just finished a stint at High-A. It's likely he'll be back there this year, as he hit .260/.283/.410 in 182 plate appearances. He's a former football player, so he's a bit behind on the development curve (i.e., don't freak out about the fact he'll be 22 in High-A this season), but he projects to be an above-average big league center fielder. Goldstein says that Szczur, "needs to improve his reads and routes," and until his approach at the plate improves, it's tough to know just what he'll end up being, despite his tools. He's a nifty project with upside, though, and the Red Sox might end up needing a center fielder after 2013 anyway.
Josh Vitters is likely the name you know the most from this list. His stock has fallen over the years, as he was drafted third overall back in 2007 and was a top 100 Baseball America prospect three times, but is now considered a three-star prospect. That said, he still shows promise. Vitters hit .283/.322/.448 at Double-A as a 21-year-old, going deep 14 times with 44 extra-base hits in 488 plate appearances overall. Defensively, more scouts than ever believe in his ability to stay at the hot corner as an average defender with a slightly above-average arm."
Jeimer Candelario is a Dominican signing from 2010, and he'll be all of 18 years old in 2011. While he was great in the Dominican Summer League, I have a hard time envisioning the Cubs giving up such a young, high-upside prospect, or Boston targeting that kind of player as compensation. That's just a personal take on what they might be searching for as compensation, though.
Trey McNutt would be an intriguing get. Goldstein ranked him as a four-star prospect in 2011, tops in the Cubs' system -- the only other four-star arm was Chris "Duchess" Archer, and he was dealt shortly after publication in the Matt Garza swap. His velocity dipped last season and his command vanished at times thanks to mechanical issues. Those can generally be worked out, but the fact they exist isn't promising, either. He'll likely repeat Double-A given those problems, but he'll just be 22 years old.
Finally, we've got shortstop Marco Hernandez. He's another international free agent, a Dominican signed in 2009. He played in the Arizona Rookie League in 2011, hitting .333/.375/.486. He doesn't have a ton in the way of projection, but Goldstein says, in a perfect world, Hernandez is "an everyday shortstop, and there aren't 30 of those in the big leagues."
Plenty of upside, plenty of intriguing names, but no hands-down superstar talent. Both sides should be happy about how this worked out if it's one of those names, as Boston would end up with even more in the ways of mid-level depth -- remember, a three-star prospect might not sound exciting, but that's basically the Red Sox system from Blake Swihart (fifth in Goldstein's rankings) to Brandon Workman (#16). More of those guys, either to promote or to deal, isn't a bad thing for this organization.
[Update 10:16 am] Alex Speier tweets that compensation will be a pitcher from the Cubs 40-man roster. That narrows things down even further, and also eliminates every single player in this article from contention.