Willingham entered Saturday hitting .250 (4-for-16) with two homers, four walks and four RBIs in five games, while Arcia has hit .429 (9-for-21) with two homers, three doubles and two RBIs.
"It makes a big difference," said third baseman Trevor Plouffe, who also homered Friday. "Those are two guys in the middle of our order we didn't have a couple weeks ago. Hammer is a guy who has a track record. He's going to do what he does. Arcia has shown he can do that. He can carry a team at times. That's something big for us."
Willingham, who suffered a small fracture in his left wrist when he was hit by a pitch on April 6, added that he believes his timing is starting to come around.
"I feel strong," Willingham said. "Timing is an everyday battle anyways."
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, and follow him on Twitter @RhettBollinger. This story was not subject to the approval of Major League Baseball or its clubs.