The move came less than 24 hours after the D-backs dealt veteran left-handed reliever Oliver Perez to the Astros. The trades also came a week after the non-waiver Trade Deadline
"For us, it was an opportunity to get a little bit younger and get some more prospects," D-backs assistant general manager Bryan Minniti said. "Both guys, Oliver and Cliff, are guys that very easily, if these deals had come to us a week or so ago, it could have happened then, too. I don't know of any rhyme or reason, maybe just those teams further identifying their needs."
MLB.com had ranked the 20-year-old Lugo as the 12th-best prospect in the Blue Jays' system, and he slots in as the D-backs' No. 17 prospect. He hit a combined .257 for Class A Lansing and Class A Advanced Dunedin.
Lugo will report to Class A Kane County.
"He's not a speed guy, but he can play the middle infield," Minniti said. "He's just an interesting tool package and another guy to add to the group of guys we have in the Minor Leagues."
Romak, 29, was hitting .289 with 33 doubles, 22 homers and 87 RBIs for Reno this year. His 26 RBIs during the month of July were the most in a single month in team history.
Hessler, 26, was 4-2 with a 1.68 ERA combined for Class A Visalia, Double-A Mobile and Reno. He will take the spot vacated by left-handed reliever Oliver Perez, who was dealt to the Astros on Friday night.
"It's the ability for us to add some more depth and more projects and more projection in the system," Minniti said.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. Jake Rill is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.