With the 2021 Major League Baseball season rapidly approaching its halfway point, many players have played their way into fans' and pundits' good graces while many others have simply faded into the background.

Then there are the ones who are somewhere in between.

We've taken a look at one player from every team who, for one reason or another, has been under heavy scrutiny throughout 2021. Some have been frustrating observers by being inconsistent or just plain underperforming. Others are pieces of trade bait whose value is rising or falling by the day.

We'll go division by division, starting in the American League East and ending in the National League West.

 

American League East

Baltimore Orioles: 1B Trey Mancini

Earlier in the season, this spot might have belonged to Ryan Mountcastle on account of the difficulty he was having living up to last year's breakout. But the 24-year-old has been hot lately with a 1.018 OPS since May 16 and is now riding especially high after a three-homer game Saturday.

After missing 2020 with colon cancer, Trey Mancini has returned to become one of baseball's greatest stories in 2021. Yet the conversation around him is already shifting to his trade value ahead of the July 30 deadline, and by nature it's going to be less focused on his comeback story and more so on his hitting.

        

Boston Red Sox: 1B Bobby Dalbec

In light of the ugly 6.21 ERA that he has through 13 starts, the Red Sox should have every reason to be impatient with alleged ace Eduardo Rodriguez. But since he's also coming off a year lost to a heart condition, there should and does seem to be an element of patience there.

Bobby Dalbec, on the other hand, has been frustrating the Red Sox all season. After busting out with a 152 OPS+ in 2020, he's regressed to an 89 OPS+ and a downright painful minus-0.7 rWAR. Understandably, the locals have questions about the length of the 25-year-old's leash.

    

New York Yankees: RHP Gerrit Cole

Granted, the Yankees have never had a star player who wasn't under the microscope every hour of every day. But with all due respect to luminaries like Aaron Judge, Giancarlo Stanton, Gleyber Torres and Gary Sanchez, nobody is asking for scrutiny right now quite like Gerrit Cole.

Even if he's living up to his $324 million deal with a 2.31 ERA, he's feeling the sting of baseball's new ban on foreign substances. To wit, his spin rate in his last start was his lowest since 2018. He's thus become one of the poster boys for MLB's sticky-stuff problem, and the question now is if he can continue to dominate without his usual spin.

        

Tampa Bay Rays: 2B Brandon Lowe

The Rays are a micro-budget, small-market team that nonetheless leads all American League clubs in wins since the start of last season. That's a charmed life if there ever was one, so what could there possibly be to complain about?

Well, maybe the early performance of Brandon Lowe. He was an All-Star in 2019 and a down-ballot MVP contender in 2020, but this year he's attracted all sorts of befuddlement as he's managed just a 101 OPS+ with a 32 percent strikeout rate. At some point, the Rays will need him to be better.

     

Toronto Blue Jays: 3B Cavan Biggio

Blue Jays fans might be frustrated that $150 million signee George Springer has played only four games all season, but it's not as if he's suffered quad injuries on purpose. The early struggles of Lourdes Gurriel Jr. and Cavan Biggio, on the other hand, are fair game.

The latter, in particular, has been a source of frustration with his disappointing 102 OPS+ and erratic defense at third base. While these issues aren't hamstringing Toronto, it is fair to wonder if Biggio has already peaked while fellow youngsters Vladimir Guerrero Jr. and Bo Bichette are still rising.