Five things to watch as MLB spring training games begin in Arizona, Florida

As always, never believe anything you see on a baseball diamond in February or March. 

So, with that out of the way, a hearty welcome back to Major League Baseball, which will stage a month of exhibitions before starting a hoped-for 162-game season April 1. 

As with all things in the era of the coronavirus, everything is subject to change — starting with regionalized play in the Grapefruit League and game lengths that can vary by the day. Yet teams and players alike have so far reported few COVID-19 cases upon intake — 14 players and six staff members among nearly 21,000 tests conducted. 

While teams will take everything on and off the field deliberately, and there's little of consequence to any single exhibition, there are a few items that will be resolved before crowds of less than 5,000 due to attendance restrictions. Here's what to watch for as games commence Sunday: 

Fallen stars

Yep, you can ignore spring results. True, you can minimize regular season stats until about Memorial Day, too. 

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Still, there's a handful of MVP-caliber talents who could stand to figure things out quickly in 2021.

"We live in a business where it’s ‘What have you done for me lately?’" says Brewers right fielder Christian Yelich, who went from NL MVP in 2018 to a desultory, .205-hitting season in 2020. "What I’ve done lately is play terribly, so I’m looking forward to a fresh start and starting a new year."

Yelich has the security of a long-term deal through 2028. Javy Baez does not. The Cubs shortstop, runner-up to Yelich in 2018 MVP voting, was totally unproductive in 2020, posting a .205/.238/.360 slash line, his .599 OPS third-worst among qualified major league hitters. Baez and fellow Cubs All-Stars Kris Bryant and Anthony Rizzo can become free agents after this season.

"I wasn't mentally ready for last year," Baez said. 

Jose Altuve (.286 OBP), J.D. Martinez (81 adjusted OPS), Kyle Schwarber (.188 batting average) — none can reverse their career-worst 2020s in a few exhibition games. Yet all could use a sturdier leg to stand on before the lights come on for real.

Return of the Klubot?

The Yankees are heavy favorites to win the AL East, and for good reason — the defending champion Tampa Bay Rays took a half-step back in the offseason while New York retained the great DJ LeMahieu and enjoys Gucci-caliber depth throughout its roster. 

Yet there's a tenuous feel to this Yankee season, tied to the many unknowns surrounding their starting rotation. 

And that's why Corey Kluber may be the most important figure to watch in the Grapefruit League West region. 

The two-time AL Cy Young winner made just eight starts the past two seasons, throwing one inning for the Texas Rangers in 2020 before a muscle tear in his right shoulder. A boffo winter workout prompted the Yankees to outbid numerous suitors, guaranteeing Kluber $11 million.

Now, he epitomizes the significant risk-reward of this roster. If Kluber is anything like the guy that struck out 1,228 batters and posted a 1.02 WHIP between 2014-2018, the Yankees will have a punishing, perhaps indomitable 1-2 with him and Gerrit Cole. 

But a breakdown would suddenly leave the Yankees with question marks throughout the rotation. Two-time Tommy John surgery recipient Jameson Taillon is the No. 3 starter, No. 5 starter Domingo German missed all of 2020 after violating MLB's domestic violence policy, Luis Severino returns midseason from Tommy John surgery and younger arms Clarke Schmidt and Deivi Garcia remain relatively unknown quantities.

That's not to say Kluber's spring results will matter. But plenty of eyeballs will be upon him.

Will the Mariners go to Jarred?

Can a 21-year-old prospect with just 21 games played above Class A ball make an entire organization squirm? 

That's the goal for Jarred Kelenic, the Seattle Mariners outfielder who, according to now-former club CEO Kevin Mather, had no shot of making the team last summer or this spring. 

Mather's many ill-advised comments resulted in his resignation, but none drew the ire of the industry like his unfiltered admission the Mariners will keep Kelenic down to harvest more years of service out of him. 

Now, the consensus top five prospect can try to force the Mariners' hand with blistering line drives and soaring home runs across the desert. Can he force his way on the squad with a Cactus League fusillade?

Sure, roster maneuvers and service-time trickery are a part of every spring. Yet, as the sport enters a pivotal year in labor relations, here's a rare case where otherwise meaningless spring plate appearances will be under heavy scrutiny. 

White Sox: Loud noises  

They are loaded with talent, big personalities and helmed by a 76-year-old manager eager to claim he can coexist with the cool kids. 

In short, how can you not keep an eye on the Chicago White Sox in Cactus League play?

Enough has been made about how Tony La Russa, already enshrined in the Hall of Fame, will relate to a fun bunch of youngsters and an intriguing youth/veteran mix in the clubhouse. 

On the field, the noise that may matter most could be Andrew Vaughn's bat.

Like Kelenic, Vaughn is a top 15-ish prospect with an advanced hit tool and an ability to help the White Sox immediately. After he went underground with all the other top prospects in 2020, Vaughn is expected to emerge almost big-league ready.

If he tears up the Cactus League, will the White Sox start him right away in Chicago, where DH at-bats are there for the taking? In this Kelenic Spring, it's another situation worth monitoring. 

Arms races

Several teams, including the Yankees and Blue Jays, will open their exhibition slate by playing seven-inning games. It's all part of a safety-first approach by almost every team to ease their pitchers into action after a mere 60-game schedule in 2020.

While the early returns can be largely dismissed — first spring training starts aren't much more than glorified live batting practice sessions, anyway — it will bear watching how quickly pitchers stretch out and if they'll stay healthy doing it. While teams were afforded 28-man rosters last year, this year it's back to 26, but with no limit on pitchers. 

So, be ready for a slew of 15-man pitching staffs and a handful of six-man rotations. For now, teams will be satisfied if they can just get their horses to the gate healthy on April 1.