The Cubs continued adding to their starting pitching depth in the past two weeks by trading for righties Eddie Butler and Alec Mills, both of whom had been designated for assignment by their old teams. Notably, the Cubs gave up prospects of at least modest value to acquire those players — righty James Farris went to the Rockies with an international bonus slot in the Butler deal, and outfielder Donnie Dewees headed to Kansas City for Mills. But the Cubs felt Butler and Mills were attracting enough interest to justify giving up talent to get them, according to ESPN’s Jesse Rogers.

“Both were getting phone calls,” Cubs GM Jed Hoyer said Thursday in an interview with ESPN 1000. “They have options. They can make starts for you. Finding guys who can make starts for you is very difficult and very expensive. We showed the appropriate urgency to get those guys.”

The fact that both pitchers had options was clearly important to the Cubs, as Rogers notes. But the team also thinks Butler, in particular, has a chance to be more than a depth starter.

“He’s an excellent change-of-scenery guy,” said Hoyer. “Our best example is Jake Arrieta. Sometimes a talented guy needs a change of scenery, and that was our logic with Eddie Butler.”

As Rogers notes, Mills was only designated for assignment when the Royals signed Jason Hammel, whose option the Cubs declined earlier in the offseason. The team’s pursuit of starting depth now raises the question of whether the team would have been better off had it simply exercised the option. But Rogers says a key reason the two sides parted ways was that Hammel had a conflicted relationship with manager Joe Maddon, who Hammel felt didn’t have appropriate faith in him and who frustrated him by pulling him out of games before he would have liked to depart. Though the option on Hammel’s contract was a team option, the Cubs allowed him to decide whether he wanted to leave, and Hammel made the call. Rogers’ sources tell him that was due primarily to his relationship with Maddon.

In any case, beyond Arrieta, Jon Lester, Kyle Hendricks and John Lackey, the Cubs now have Mike Montgomery and Brett Anderson, along with Rob Zastryzny, Ryan Williams and now Butler and Mills. Of the last four, it has yet to be determined who the Cubs will turn to first should they need extra rotation help in the big leagues.