Now we know who those players were.

According to CBSSports.com, Arizona was set to receive three pitchers and a shortstop.

The deal would have sent three or four players back to Arizona, according to CBSSports.com sources. Included among those players would have been relievers Charlie Furbush and Stephen Pryor, minor-league shortstop Nick Franklin and prized pitching prospect Taijuan Walker.

Before settling on Walker, the Diamondbacks also discussed top Seattle pitching prospects James Paxton and lefty Danny Hultzen. The clubs also discussed the possibility of a second player accompanying Upton to Seattle in the deal. The identity of that player, believed to be a low level minor leaguer, is not known.

Walker, 20, would be the prize of the deal. The number two prospect in the Mariners organization according to Baseball America, he is a right-handed pitcher, he's posted a 14-16 record with a 3.83 ERA over the course of three minor league seasons. He's struck out 240 batters in 230.1 innings of work.

Furbush and Pryor are both relief pitchers. Furbush posted a 5-2 record with 2.72 ERA in 46.1 innings of work last year, while Pryor went 3-1 with a 3.91 ERA in 23 innings.

Franklin, who is a 21-year-old shortstop, is regarded as a good prospect at a position where the D-backs have some uncertainty. He's posted a .283 batting average over four minor league seasons, but hit just .243 for Triple-A Tacoma last year.