MLB Rumors: 10 prospects who should start the season in the big leagues

Roster spots are still up for grabs around MLB, and these ten prospects should make their way onto an Opening Day roster.

For most MLB players, Spring Training is an exercise in getting ready for the season with an assurance that a spot on the roster is guaranteed. Most rosters around the league have only two or three spots on the Opening Day 25-man truly open during camp. Typically, those spots are reserved for role-playing veterans who show they have enough left in the tank to continue holding down an MLB job.

Every so often, however, a top prospect comes along and stakes his claim to an unexpected roster spot. Aaron Judge, for example, entered camp last year without a firm grip on a starting job and emerged as an MVP candidate. Similarly, Trey Mancini slugged his way onto the Baltimore Orioles, making the team only because the team could shuffle its rotation in April, before going on to finish third in the AL Rookie of the Year vote.

While teams will still attempt to keep their best prospects down to start the year, whether for service-time manipulation or to give a few extra months of maturation, these 10 prospects have been wowing in Spring Training and should be given a chance to come north with their respective clubs for Opening Day.

10. Jack Flaherty

The St. Louis Cardinals will welcome one top prospect, Luke Weaver, to their rotation on a permanent basis this season. Another, righty Jack Flaherty is also making a case of his own. With Adam Wainwright coming off a down year and Japanese import Miles Mikolas struggling in his first MLB Spring Training action since 2014, the Cardinals need to keep their options for fifth starter open as long as possible.

Flaherty made his MLB debut late last season and struggled with his command and the longball. Those issues should not sour the Cardinals on the 22-year-old. Since being drafted, he has bumped his velocity from the low nineties up to 96 mph. Flaherty also throws two good breaking balls and is improving his changeup.

As he has moved through the farm system, Flaherty has improved his command at each stop, lowering his walk rate to 2.1 per nine last year. He has swing-and-miss stuff and has gotten better at locating his pitches within the strike zone. Flaherty will be the first man up if Wainwright and Mikolas cannot perform.