Hernandez, a three-time All-Star and the 2010 AL Cy Young Award winner, is due to report to Mariners spring training headquarters Tuesday for his physical.
The two sides have been working on a seven-year, $175 million deal but the deal has yet to be announced. There has been speculation and reports about an injury to Hernandez's pitching elbow that could be slowing the negotiations.
Zduriencik said the Mariners and Hernandez's agents, Wil Polidor and Scott Pucino, have engaged "significantly" in talks.
"I think things have been very positive. There's been a good tone to our discussions," Zduriencik said. "I hope on a positive note that sooner or later we'll be able to announce something. But anything of this magnitude, in terms of years and dollars, just takes time to work things out."