MESA, Ariz. -- It was an unusual sight, particularly for a million-dollar athlete. Kyle Schwarber came walking through the Chicago Cubs' spring clubhouse one morning with Tupperware in his hand.

Since when do major league baseball players bring their leftovers to work? The answer: since said player is trying to maintain a strict diet.

What started as an offseason lifestyle change for Schwarber has continued throughout spring training. Call it Phase II of The Comeback. First came losing 20 pounds and improving his athleticism. The next step, playing out this spring, is about taking all those hours at the gym during the winter months and putting the results to work in Cactus League games.

Even though they’re just spring contests, Schwarber has dominated them the same way he did his offseason plan. Entering Thursday, Schwarber is hitting .429 with a .500 on-base percentage against left-handed pitching. It’s no surprise to scouts who have followed the Cubs and come away impressed with what they have seen.

“He’s using his hands more,” one National League scout said recently of Schwarber’s swing. “It’s more compact. He’ll be able to get to more fastballs. Other than that, it looks the same.”

Schwarber's manager has noticed the "more hands" idea too.

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“The one thing I’m seeing is he’s not swinging as hard,” Joe Maddon said. “It’s more under control. More hands, less arms. And with that, it looks easier. He’s doing it easier. He’s eased up a bit. And better adjustments with two strikes.”

Schwarber, 25, has been hitting the cover off the ball -- he drove a sacrifice fly to the center-field wall off the end of his bat Wednesday, then homered to left in his next at-bat -- but the key to his comeback might actually be in the balls he doesn’t hit. Laying off borderline pitches was Schwarber’s calling card early in his career, particularly during his miraculous return for the 2016 World Series. But last season, he swung and missed at high fastballs more often than anyone associated with the Cubs would have liked. So when you see eight walks in 50 plate appearances this spring, you see progress -- or perhaps simply a return to the old Schwarber.

“The game is going up there now,” Schwarber said. “You don’t want to chase, but you have to know the top of the zone. ... You see more bullpen guys, especially, trending up top.”

One recent sequence might best illustrate Schwarber’s current strike-zone awareness: He took a four-pitch walk against Cincinnati Reds pitcher Kevin Shackelford. Three of the pitches were on the border, but Schwarber didn’t even flinch. Maddon often says, "If you’re walking, you’re hitting," and that currently applies to Schwarber. And even if he does swing at a borderline high pitch, his "hands" approach should help.

“He’s working on laying off those things and attacking it if he has to,” Maddon said. “You can’t really do it if you’re all about your arms. You can’t get to the high ball properly. Think of Vlad Guerrero. I always thought he looked like he was hitting a piñata at a birthday party. His hands were always adjusting to where the ball was. That’s what a good, handsy hitter does. I’ve seen more of that.”

Besides the time Schwarber put in at the gym during the offseason, he spent money on improving his 2018 forecast. At a cost of about $3,500, he bought a new pitching machine. For those cynics who said losing weight alone wouldn’t make him hit better, Schwarber answered by taking swings -- a lot of them. In an effort to play every day -- not just against right-handers -- he positioned the machine on the left side of the pitcher’s mound and set it to throw all sorts of pitches, from fastballs to curves. Over and over again, Schwarber mimicked hitting off a lefty. The results showed up this spring.

“He’s calmer against a lefty now,” a second scout observed. “He’s using his hands to get around on some balls that perhaps got by him last year.”

Each time a scout has noticed a nuance while Schwarber rockets baseballs across Cactus League outfields, Maddon has almost echoed the same thought.

Chicago Cubs' Kyle Schwarber bats during the first inning of a spring training baseball game against the Chicago White Sox, Tuesday, Feb. 27, 2018, in Mesa, Ariz. Carlos Osorio/AP Photo

“I don’t like when hitters swing at a baseball,” Maddon said unsarcastically. “Hit it, strike it, throw the head at it. I think he’s doing more of that. He’s not swinging at it with his arms.”

Schwarber’s take is less drastic. He was looking for more quickness, which he knew he would get with the drop in weight. There was little tinkering with the actual swing.

“It was more cleaning up some things,” he said. “Maybe making it a shorter swing. Things like that. ... My goal is to put the barrel on the ball. That’s all I want to do. And go from there.

“I just want to lock into it even more. To stay in my zone and not chase.”

Playing every day is just the first regular-season goal for Schwarber. Playing nine innings on defense might be the next one. He’s clearly still a work in progress in the outfield -- scouts were unanimous in that evaluation -- but his first step alone should allow him to get to more balls. In fact, his biggest task might be understanding which balls he can’t get to, kind of like the defensive version of a high fastball.

“If it's hit behind him, he needs to back off and play it off the wall,” scout No. 1 said. “That can be the difference between a single and double or double and triple.”

Schwarber admits that he is still learning. At least he has a strong catcher’s arm and is fairly accurate with it. The bottom line: If he hits, it won’t matter much how he plays in left. The Cubs have always felt that way, but a little better defense to go with a big improvement at the plate could return Schwarber to legendary status in Chicago and the baseball world. Who doesn’t love a comeback story?

“He’s kind of on a mission,” Cubs strength coach Tim Buss said.

As for that Tupperware, Schwarber also spent money on a personal chef, both in Florida during the winter and in Arizona over the past six weeks. Sometimes it just made more sense to bring his lunch.

What was in the plastic, anyway?

“Chicken," Schwarber said. "Lots of chicken.”