Over his past 12 games entering play Saturday, the Rays' center fielder hit .400 with three home runs, six doubles, 13 RBIs and a .509 on-base percentage.
Rays manager Joe Maddon attributed Upton's recent impact to the fact he's "accepting his walks."
"He's organized his strike zone again, he's not chasing out of the zone, and because he's not chasing when they come to him, he's been hitting the ball well," Maddon said. "Primarily, that's it."
Upton's younger brother, Justin, plays for the Arizona Diamondbacks and is a National League MVP candidate. Maddon was asked if he felt like seeing his brother's performance had inspired the elder Upton, to which he deferred the answer to Upton before adding that he's noticed a "real focus about him, conversationally."
"I listen to what he's saying among the other guys," Maddon said. "It's different in all the best ways. ... He's talking from the heart right now, and I think it's impacting his play in a positive way.
"He wants us to play in the World Series this year. He likes being in the World Series. He's been there and he did a real good job on the big stage in the past, and he kind of likes that stuff. And so I think that's what you're seeing right now. He's been there before, he knows what it feels like, he knows what it takes. I know he's young, but that's what I'm kind of getting about him right now. That's what I'm seeing."