Are the Diamondbacks open to trading Zac Gallen?

DALLAS — On Dec. 5, 2018, Diamondbacks general manager Mike Hazen traded All-Star first baseman Paul Goldschmidt to the St. Louis Cardinals. He has spent the better part of the past six years regretting it.
In return, the Diamondbacks received right-hander Luke Weaver, catcher Carson Kelly, infield prospect Andy Young and a Competitive Balance Round B draft pick.
With Goldschmidt just a year away from free agency, it appeared to be a reasonable return. The Diamondbacks were not optimistic about re-signing him, and they did not want to lose him for nothing. But the trade did not pan out as Hazen hoped.
This offseason, the Diamondbacks are in a similar situation; their best starting pitcher, Z...