"His on-base percentage is right around 30 percent. He's hitting like .150, so its 150 points above his batting average -- that's phenomenal," Maddon said. "You know he's going to start hitting. ... When [your on-base percentage is] 100-150 points ... over your batting average, that really speaks to walking, having a good eye, etc."
Through play on Tuesday, Upton was batting .151 with a .189 slugging percentage and a .297 on-base percentage. Maddon believes Upton's offensive timing is improving.
"These are the situations I want him to work through," Maddon said, "because when he gets that going, then we get going."
The 24-year-old center fielder is 1-for-24 since April 23. Upton, however, walked twice and stole two bases in Tuesday's game against the Twins.
"Getting on base is going to make a huge difference in getting the offense rolling," Maddon said. "[Upton] and Carl [Crawford] at the top can be devastating once they get together as a unit."
Upton iced his left shoulder prior to Wednesday's game. He appeared agitated when exiting the trainer's room.
"He might have gotten a call from his girlfriend," Maddon quipped. "As far as I know, everything is fine."
Upton declined comment.
At least one teammate believes the reports of Upton's struggles have been exaggerated.
"He's hit a lot of balls hard," Ben Zobrist said. "What looks like a slump a lot of times is just the ball isn't bouncing your way. Like last night in the eighth inning, he smoked that ball to left field, and if that ball is a little bit to the right or to the left, it's probably a double, scores those two runs [and] maybe we go on to win that game. We haven't had things go our way at certain points in the game. That's going to swing to our favor at some point."
Thor Nystrom is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.