The St. Louis Cardinals roster has some serious questions entering the month of June. Will they be buyers or sellers at the deadline?

The NL Central is wide open, but that doesn't mean this Cardinals team has a legitimate chance at making a postseason run. With the Brewers, Pirates, Reds and Cubs in front of them, St. Louis has a lot of work to do to prove to this front office that they should be buyers at the trade deadline. John Mozeliak was adamant just last week that he wanted to add to the roster come late July. However, should the Cards losing ways continue, there's no reason to hold onto rentals, or make a major addition for that matter.

Making the right moves this month could play a major role in determining St. Louis' direction. Right now, they don't have one, and Oli Marmol isn't helping. The Cards need to figure out what they have in some of their younger players like Jordan Walker and Nolan Gorman. Also, who out of their outfield logjam should be trade assets, and who is untouchable down the line?

These three players, however, are more worried about their immediate future, not late July.

Cardinals who won't be back: Matthew Liberatore

Maybe this will be the time Matthew Liberatore finally sticks in the major leagues, but my money is against it happening. Liberatore is a top-100 prospect for a reason, but St. Louis has yet to give him much of a chance. Every start is greeted with far too much pressure for the 23-year-old pitcher, with the fear that should he struggle he'll end up right back in Memphis.

St. Louis has a history of mismanaging young pitchers. Look no further than Sandy Alcantara and Zac Gallen. Yet, the same player development staff is largely in charge, making their treatment of Liberatore look all too familiar.

So, it's with that knowledge that Liberatore could very well end up back in the minors by late June. He was gifted a spot in the rotation for now, but Liberatore has two pitchers on his tail in Steven Matz (a high-priced free agent) and Jake Woodford, who is soon to be activated off the injured list.

If Liberatore can outlast both of those pitchers, he will have truly earned his spot. Here's to hoping I'm wrong, at least this time.

Cardinals who won't be back: Tres Barrera

As great as his mustache may be, Tres Barrera isn't productive enough to keep in the lineup, even twice a week. Andrew Knizer is the starting catcher for now, and Willson Contreras is earning some reps back by the week.

As Sports Illustrated noted upon his promotion, Barrera was never meant to play a large role in St. Louis. He was, however, an answer to some of their questions behind the dish:

"At this point, the Cardinals could use all of the help the club could get. St. Louis' starting pitching has been the club's biggest issue, but Wainwright hopefully should help with that. Barrera may not play a major role, but he can give the club more depth. Hopefully, these moves can help point the Cardinals in the right direction."

Now that Contreras has proven himself capable and made some necessary improvements, he can at least be counted on to back up Knizer and work with the St. Louis pitching staff. Oddly enough, it seems the Cards have blamed just about everyone in the organization but the front office for their pitching woes. Adam Wainwright is fine, as is Miles Mikolas. But what the Cards are lacking is a true ace.

The Cards failed to answer the call this offseason, when they could have signed the likes of Jacob deGrom or Carlos Rodon, among others. They missed out on Sandy Alcantara and Zac Gallen, both of whom were in their system.

Promoting a player like Barrera was always a short-term fix for the Cards. He won't be missed, especially once Contreras gains his footing behind home plate.

Cardinals who won't be back: Oscar Mercado

The St. Louis Cardinals need to clear up their outfield jam, but this isn't the roster move fans were hoping for, at least not yet.

Several Cards outfielders are currently on the injured list, hence the call-up of Jordan Walker. Oscar Mercado is filling one of those voids as well. However, when Dylan Carlson and Lars Nootbaar are activated off the injured list, which should happen in the month of June, someone will have to go back down. Expect that someone to be Oscar Mercado, assuming he doesn't hit the cover off the ball.

Mercado is already losing work to the likes of Brendan Donovan and Alec Burleson, two players with a more proven track record in the majors. While sending Mercado down makes sense once their two starting outfielders return, it's not so simple, as outlined by MLB Trade Rumors:

"Mercado is out of minor league options, so it could be a short stay on the big league roster for him once O'Neill and/or Carlson can return to the lineup. The Cards won't be able to send Mercado down without first passing him through waivers, which would make him a DFA candidate once the outfield is at full strength."

Nonetheless, Mercado is a player the Cards can afford to lose, as much as they make like him off the bench. Expect him to hit waivers at some point this month, and potentially leave St. Louis altogether.