Darvill, 22, a fifth-round pick in 2009, began this season at Class A Kane County, and batted .347 in 15 games before he was promoted to Class A Advanced Daytona, where he hit .253 in 79 games. A left-handed hitter, he played primarily at second base, but also played third and shortstop.
Albert Almora, the Cubs' No. 1 pick in the 2012 First-Year Player Draft and ranked by MLB.com as the organization's No. 2 prospect, was on the Mesa taxi squad, but now will have the chance to play every day, Epstein said.
The Cubs also pulled Arodys Vizcaino off the AFL roster so he could pitch in instructional league and are expected to add a pitcher to Mesa.
• Second baseman Darwin Barney did not start Tuesday but will be back in the lineup on Wednesday in the home finale. Barney was batting .156 in 20 games this month. Could he be worn down?
"You never know," Sveum said. "I don't know about physically, but mentally he's probably not where he wants to be."
• The Cubs have four players converting to catcher during instructional league, including Ben Carhart, Gioskar Amaya, Giuseppe Papaccio, and Jordan Hankins. Epstein said the moves were an "experiment" for the quartet.
Carhart played first and third with Daytona this season, batting .247, while Amaya played second base for Kane County. Hankins and Papaccio, both infielders, were selected in this year's Draft in the 11th and 18th rounds, respectively.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.