The Cubs and Athletics are in serious discussions regarding a major swap that would deliver Chicago starters Jason Hammel “and/or” Jeff Samardzija to Oakland, report Ken Rosenthal and Jon Morosi of FOX Sports (Twitter links). Top Oakland prospect Addison Russell has been discussed, according to the report.

Needless to say, a deal involving both Hammel and Samardzija would represent a stunning early turn in the market. The pair of Cubs hurlers has long been rumored to be among the best arms likely to change hands over the summer. But both were expected to have many suitors, some (but not all) of which would likely overlap.

Though Hammel is expected to bring back some value, there is little doubt that Russell would only be involved if Samardzija was also on his way to Oakland. The 20-year-old shortstop is far and away the A’s best-regarded prospect, with a wide consensus that he is one of the twenty best pre-MLB players in the game. ESPN.com’s Keith Law (Insider link) ranked him as the third-best overall prospect coming into the season, lauding his outstanding across-the-board tools, projectable power, elite hands and arm at short, and overall feel for the game.

Indeed, it is arguable that Russell would be too great a return even for Samardzija. On the other hand, it is difficult to see the A’s landing Samardzija (or any other starter at or above his level) without including Russell. The fall-off in the A’s system comes fairly quickly. Billy McKinney is the team’s consensus second-best prospect, but he (like much of the rest of the organization’s best talent) has yet to advance above High-A ball and does not rate amongst the game’s best-rated young players.

For the A’s, the addition of at least one starter — if not two — makes a good deal of sense. The rotation has been good thus far, but clearly could benefit from an upgrade at the top and/or depth at the back for the playoff push.

Of course, Oakland could also stand to upgrade its options at second base. As Dave Cameron of Fangraphs notes on Twitter, that is another area where the Cubs could potentially add value in a hypothetical deal. Indeed, Luis Valbuena, Emilio Bonifacio, and Darwin Barney are all capable of manning the keystone. And it is not inconceivable that a deal could deliver a somewhat lesser prospect (or prospects) back to Oakland, in order to balance out the A’s sacrifice of future value. Ultimately, there are many plausible permutations that one could imagine coming to pass.