I don't know if the Cubs truly need to trade for pitching. They are basically going to fill the team with rookie contracts with position players. They should have a ton of money to spend on pitching. I mean if you can get a young ace type in a trade then yea but I wouldn't go for older types. I would love to try to nab Dylan Bundy somehow.
2015 F/A SP list:
Brett Anderson (27) - $12MM club option with a $1.5MM buyout
Homer Bailey (29)
Josh Beckett (35)
Chad Billingsley (30) - $14MM club option with a $3MM buyout
Joe Blanton (34) - $8MM club option with a $1MM buyout
Wei-Yin Chen (29) - $4.75MM club option with a $372K buyout
Kevin Correia (34)
Johnny Cueto (29) - $10MM club option with an $800K buyout
Ryan Dempster (38)
Yovani Gallardo (29) - $13MM club option with a $600K buyout
Edgar Gonzalez (32)
J.A. Happ (32) - $6.7MM club option
Luke Hochevar (31)
Hisashi Iwakuma (34) - $7MM club option with a $1MM buyout
Jair Jurrjens (29)
Kyle Kendrick (30)
Clayton Kershaw (27)
Aaron Laffey (30)
John Lannan (30)
Justin Masterson (30)
Brandon McCarthy (31)
Brandon Morrow (30) - $10MM club option with a $1MM buyout
Charlie Morton (31)
Jeff Niemann (32)
Ross Ohlendorf (32)
Felipe Paulino (31)
Jake Peavy (34)
Clayton Richard (31)
Max Scherzer (30)
Chris Volstad (28)
Carlos Villanueva (31)
Not much to pick from. They maybe better off using the surplus hitting to acquire SP with team control. Off that list Kershaw should be locked up. Scherzer maybe traded this off season. Kendrick is as good as they have now.
This off season's SP talent looks better IMP.