The Cubs have been pursuing Darvish, according to rumors, all offseason, and this is a significant commitment to the best free agent pitcher on the market. Six years at $25 million per year was around what Darvish was expected to command this offseason, though reports had indicated he was aiming for the seven year, $175 million deal that Stephen Strasburg received from the Washington Nationals before reaching free agency.
While the Texas Rangers had widely been reported to have interest in a reunion with Darvish, the indications had consistently been that the team wasn't willing to pay top dollar for him, and given the current state of the team, while I would have loved to have seen Darvish return to Texas, I can't blame them for passing at 6/$150M.
Now we shall see if this results in addition movement on the free agent pitching front. The Cubs were the team that seemingly had the most interest in free agent pitcher Alex Cobb, particularly with manager Joe Maddon and pitching coach Jim Hickey both having originally been with the Tampa Bay Rays, Cobb's old team. Meanwhile, Jake Arrieta, who was with the Cubs the past few years, is still on the market, as is Lance Lynn. That trio is considered the top options on the market now that Darvish is off the table.
UPDATE — Reports now indicate the deal for Darvish is 6 years, $126 million guaranteed, with the potential for the full amount to be $150 million.