Much is made at this time of year about positional uncertainty. Spring Training presents prospects with the chance to accelerate their path to the big leagues, and veterans to solidify their roles. With games just barely underway in the Cactus and Grapefruit Leagues, for some the long winter's personnel shuffling has left an unclear picture of who will contribute where.
Here is a glance at some noteworthy performances from Saturday by those competing for position or roster spots this spring.
Keon Broxton, Brewers, OF
Following its acquisition of Christian Yelich and Lorenzo Cain, Milwaukee finds itself with a retooled outfield and limited space for incumbent center fielder Broxton.
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Broxton made an early impression Saturday against the Angels by homering off two-way phenom Shohei Ohtani in the much-anticipated -- and otherwise impressive -- debut by the Japanese superstar. Broxton unleashed the line drive over the left-field wall to lead off the second inning.
To account for their outfield surplus, the Brewers are experimenting with Ryan Braun at first base this spring. Right fielder Domingo Santana's 30 home runs last season will almost assuredly keep him in his current post, should the club not trade him for much-needed depth in their starting rotation. Because Broxton has one Minor League option left, the Brewers could have him start the season in Triple-A, barring injury attrition within the outfield.
Dominic Smith, Mets, 1B
Following a lapse that stirred new Mets manager Mickey Callaway, first-base prospect Smith was benched from a game he was slated to start Friday for showing up late to the club's complex in Port St. Lucie, Fla. Smith took accountability for his tardiness. A day later, Smith went 1-for-1 and was hit by a pitch in the Mets' 10-5 loss to the Cardinals. He also made an athletic stretch to scoop a low throw and nab Jose Martinez on an infield groundout.
Smith, 22, is already facing an uphill climb to become the Mets' everyday first baseman. After the club traded Lucas Duda last July, Smith made a 49-game debut, in what was essentially an audition for the 2018 job, but struggled to a .198/.262/.395 slash line that, in part, prompted the Mets to trade for veteran Adrian Gonzalez. The Mets' No. 7 prospect, Peter Alonso, who started in place of Smith on Friday, is also vying for at-bats this spring.
The ambitious Smith has an outside chance at making the club's 25-man roster.

Sean Newcomb, Braves, SP
While Newcomb clearly has an upper hand among five Braves starters vying for the club's final two rotation spots, management has made it clear it wants the young southpaw to avoid complacency.
Newcomb allowed an unearned run during his one inning against the top of the loaded Astros lineup. Brian McCann grounded into a forceout that scored Marwin Gonzalez, who had reached third on a fielding error. Newcomb needed two batters to settle in, after surrendering a first-pitch, leadoff double to Gonzalez and walking Jose Altuve on four pitches. He then punched out Carlos Correa and Yuli Gurriel looking on three straight pitches each.
Newcomb, 24, showed flashes of promise as a rookie in 2017, beginning his career with a 1.48 ERA over his first four starts last June. A rough outing on July 4 -- against the Astros -- ignited a two-month stretch in which the Braves lost nine of his following 11 starts. He finished the season 4-9 with a 4.32 ERA.
General manager Alex Anthopoulos and manager Brian Snitker have said that only Julio Teheran, Mike Foltynewicz and Brandon McCarthy are sure locks for the Opening Day rotation, with left-handers Newcomb, Luiz Gohara, Max Fried and Scott Kazmir, and right-hander Lucas Sims competing for the final two spots.

Tom Murphy, Rockies, C
A postseason club that last season leaned on Trade Deadline acquisition Jonathan Lucroy to help guide its young starters, Colorado is hoping its young catching tandem of Murphy and Tony Wolters can take a step toward weightier contributions in 2018. Of the two, Murphy has more upside with his bat -- last spring, teammates said he was the strongest player on the team -- but he struggled to exploit it during a 1-for-24 showing in 12 big league games.
Murphy went 0-for-3 with two strikeouts on Saturday against the Reds before being lifted for prospect Anthony Bemboom. This could be a revealing spring for Murphy, whose 2017 campaign was largely a wash after he suffered a broken right forearm and wrist last March.
Though the young catching depth has shown upside, particularly Wolters -- who hit .300 through the first two months of '17 before fatigue caught up with him -- the Rockies signed veteran Chris Iannetta to be the primary catcher and provide stability. Iannetta and Murphy both hit right-handed, while Wolters hits left, thus creating more of a disadvantage for Murphy to potentially platoon against lefty pitching.
Bud Norris, Cardinals, RP
One of the chief unknowns for the postseason-hopeful Cardinals this spring is the ninth inning. Manager Mike Matheny has been deliberately vague about who will close, so when the club signed journeyman Norris -- who has started, relieved and closed -- intrigue piqued.
Norris, who saved 19 games for the Angels last year, pitched the fourth and fifth innings Saturday, giving up two earned runs on three hits -- including a homer to Mets prospect Luis Guillorme -- and striking out one.
Norris is vying for high-leverage innings, but is likely down the depth chart from free-agent acquisition Luke Gregerson, who saved 15 games for the Astros in 2016. Left-hander Tyler Lyons is also believed to be strongly considered, should Gregerson struggle. Other high-velocity options include Conner Greene and Dominic Leone, in addition to Alex Reyes, who is returning from Tommy John surgery and viewed as a dark horse for the role, having come up as a starter.

Ronald Acuna Jr., Braves, OF
Acuna, MLB Pipeline's No. 2 overall prospect, is in his first (and likely final) big league Spring Training as a full-time Minor Leaguer, though it's believed that he could propel his path to the Majors with a strong showing in Grapefruit League play.
On Saturday, he didn't get off to the start he'd hoped for, going hitless in three at-bats against the Astros with two strikeouts, and perhaps tempering the lofty ambition he's projected. However, he did pull a number of towering home runs during batting practice at the Astros' complex, showcasing his power potential.

"Everything felt the same," Acuna said. "My focus was to go out there and give it my all and give my best effort. The results weren't there, but tomorrow is another day. I'll get after it again."
Acuna, 20, started on Saturday in center field, though he will likely slot into a corner spot when he cracks the Major League roster, as center is occupied by reigning Gold Glove Award winner Ender Inciarte. Lane Adams is currently slated to start in left, and Nick Markakis in right.