The South Florida Sun-Sentinel reported the two sides had agreed to terms, and Krook declined a reduced offer. And the Miami Herald added that Krook is hampered by a left shoulder ailment.
Technically, Krook could change his mind and either accept the reduced offer or continue negotiations. Teams have until July 12 to sign their Draft picks. So, the southpaw has until then to reconsider. However, a source added that there is "no chance" of that happening.
The Marlins continue to negotiate with their first-round pick, third baseman Colin Moran from the University of North Carolina.
Miami is confident that they will agree to terms with Moran, the sixth pick overall in the Draft.
Krook was a competitive-balance Round A selection that the Marlins acquired from the Pirates as part of a trade last July. Miami sent Gaby Sanchez to Pittsburgh for Gorkys Hernandez and the pick.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro. This story was not subject to the approval of Major League Baseball or its clubs.