Top prospects waiting in wings as June approaches

George Springer's recent torrid streak for the Houston Astros is leaving little room for doubt about his future … or present. His bat speed is ferocious. Springer's hitting eye is improving, seemingly on a nightly basis. He looks great in the outfield.

Springer, 24, entered the season as MLB.com's 21st-ranked prospect, and he made his Major League debut on April 16. He understandably struggled out of the gate while playing every day. Since then, however, Springer has been smoldering. After going 1-for-4 on Tuesday night, he had a line of .268/.350/.493 and eight homers and 19 RBIs since May 8.

"He got out to a slow start, and the game was kind of fast and he kind of pumped the brakes," Astros manager Bo Porter said. "Now, once he slowed the game down, you're starting to see his natural talent pretty much just take over."

Once again, Springer is proving that you don't have to have much big league experience to shine. We've seen it over the past few years with phenoms such as Mike Trout, Bryce Harper, Jose Fernandez and Wil Myers. All four came up after Opening Day and impacted their leagues so much that they were all Rookie of the Year Award winners.

And while Springer is the early favorite for the American League Rookie of the Year Award this year, it's fun to guess which players still lingering in the Minor Leagues might also have the chance to contend for a Rookie of the Year Award.

Here's a rundown of five possibilities as June approaches:

Gregory Polanco, OF, Pirates: Polanco, MLB.com's 12th-ranked prospect, has been so good in Triple-A this year (.345, six homers, 43 RBIs, 10 stolen bases through Tuesday) that fans have been clamoring for his promotion to the Majors. The Bucs, however, have been steadfast in their insistence that the 22-year-old needs more seasoning in Triple-A.

"The reality is, our roles come with tough and unpopular decisions," Pirates general manager Neal Huntington said a few weeks ago. "Our job is to make sure we make the right decisions for this organization for the righter reasons, and we believe we're doing it.

"Our job is to put [Polanco] in a position to be successful, and to be successful quickly -- to put this young man in position to thrive from Day 1."

Javier Baez, SS, Cubs: Baez is the No. 6-ranked prospect, and he's now starting to play up to that lofty rating. Baez, who hit 37 homers and drove in 111 runs in the Minors last year, began 2014 in a bad slump and was slowed by a sprained left ankle. But he's been hitting his way out of it.

Baez has raised his batting average to .225 and has seven home runs and 25 RBIs in 39 games this year.

Noah Syndergaard, RHP, Mets: MLB.com's No. 10-ranked prospect, who has hit the upper 90s with his fastball, was expected to make it to the big club at some point in the year, a la Zack Wheeler in 2013, but he's been passed on that track by Rafael Montero and Jacob deGrom.

Syndergaard had improved of late after a rough start with Triple-A Las Vegas, going 2-0 with a 3.14 ERA and 36 strikeouts in his past 28 2/3 innings, but the team has put him on the shelf now with flexor-pronator (forearm) strain in his right arm, and he will head to New York to be examined by team doctors this week.

"We're very concerned about it," Mets manager Terry Collins said. "I know a lot of guys that go to the doctor and it's nothing. But I know some that go to the doctor and it's an issue. So anytime you're going in and the word 'elbow' shows up and you throw as hard as he does, it's a concern."

Archie Bradley, RHP, D-backs: Bradley was one of Arizona's final cuts of Spring Training, even at age 21, but he struggled early this year at Triple-A Reno (1-4, 5.18 ERA). He then hit the disabled list with elbow soreness. The good news is that there was no structural damage in the joint for Bradley, who is MLB.com's No. 4-ranked prospect.

Bradley threw off flat ground earlier this week and was pain-free. He is slated to throw a bullpen session soon.

Oscar Taveras, OF, Cardinals: Taveras is MLB.com's No. 2 overall prospect, and for good reason. He's hit at every level of the Minors and is raking again this year, bringing a .323/.369/.527 line plus seven homers, 40 RBIs and 15 doubles in his first 186 at-bats this year for Triple-A Memphis.

The question, as always, is when St. Louis will deem Taveras ready for a big league outfield that is crowded once again.

Others to watch: Byron Buxton, OF, Twins (No. 1), injured; Taijuan Walker, RHP, Mariners (No. 5), injured; Kris Bryant, 3B, Cubs (No. 8); Francisco Lindor, SS, Indians (No. 9); Addison Russell, SS, A's (No. 11), injured; Jon Gray, RHP, Rockies (No. 13); Maikel Franco, 3B, Phillies (No. 22); Alex Meyer, RHP, Twins (No. 24); Andrew Heaney, LHP, Marlins (No. 25); Henry Owens, LHP, Red Sox (No. 26); Joc Pederson, OF, Dodgers (No. 29); Eddie Butler, RHP, Rockies (No. 33); Allen Webster, RHP, Red Sox (No. 38); Jon Singleton, 1B, Astros (No. 42).