Gerrit Cole was the latest top prospect to debut in the major leagues.
"Knocking Down The Door" is the phrase I use to describe players on the verge of a big league call-up based on their strong performance in the upper minors.
In many cases, however, it can still take an injury to finally open that door, as was the case this week with Pittsburgh Pirates' top pitching prospect Gerrit Cole.
The 22-year-old debuted on Tuesday after Wandy Rodriguez was scratched due to a forearm injury, but he was already making a strong case to join the Pirates, whether there was a spot available or not.
He hadn't allowed run in his last 19 innings at Triple-A , which is a heck of a way to end his minor league career if he were never to return. After beating the Giants with an impressive performance (6.2 IP, 2 ER, 7 H, 0 BB, 2 K), that could very well be the case for Cole.
Here are eight more top prospects who are currently trying to "knock down the door" and could be the next to join Cole in the majors.
The D'backs have been patient with their top pitching prospects, particularly Trevor Bauer in 2012. They've also been reluctant to give a permanent spot to lefty Tyler Skaggs, who was their top pitching prospect coming into the season.
It could be a different case with Archie Bradley, who has a 1.31 ERA with 34 walks and 90 strikeouts in 75.2 innings between Double-A and High-A this season.
At just 20 years old, it's becoming apparent that Bradley has figured things out this season and is now capable of making an impact in the majors.
It may be a year or two earlier than expected after he showed some flaws in his first full professional season in 2012 (84 BB in 136 innings with Low-A South Bend) but he has frontline starter potential and he won't be in the minors much longer if he can continue to show command of his mid-90's fastball and his plus breaking ball.
A midseason promotion to Double-A in 2012 resulted in a mediocre .678 OPS in 79 games for Castellanos.
However, the Tigers kept moving him up the ladder to Triple-A to begin the 2013 season. When an organization advances a young player with no record of success at the previous level, that's a pretty good sign that they believe in the player's talent and ability to handle the challenge.
So it figures that the Tigers probably aren't too surprised that the 21-year-old Nick Castellanos has been one of the best hitters in the minors as of late. Over his last 10 games, he's hitting .439 (18-for-41) with four homers, 10 runs batted in, six walks and just two strikeouts.
With Andy Dirks struggling this season and currently out of action as he rests his sore knees, there's a chance the Tigers give Castellanos a chance to claim the left field job for the remainder of the season.
Nick Castellanos has been REEE-diculous over past month at Triple-A: .378/.481/.631, 13:22 K:BB. May see him with #Tigers before AS break— Jason Catania (@JayCat11) June 13, 2013
After being bypassed for a big league call-up for journeymen Samuel Deduno and P.J. Walters last month, it was clear that the Twins wanted to be patient with Kyle Gibson, who threw two shutouts in May and had eight scoreless innings in another start.
While Deduno and Walters have actually been solid during their time with Minnesota, Gibson continues to make a case for a call-up with back-to-back quality starts (13 IP, 3 ER, 11 H) to lower his ERA to 3.16 in 13 Triple-A starts. If his next start is a good one, it could be his last in the minors.
There's a chance the 25-year-old is working on an innings limit after he missed most of 2012 while recovering from Tommy John surgery. If that is the case, that's all the more reason to bring him up soon so that he's able to get as much big league experience as possible before entering his first full season in the majors in 2014.
Grant Green was a shortstop when he was drafted in the first round of the 2009 draft and the A's gave him a chance to play the position in 2010 when he made 37 errors in 114 games.
Since then, the A's have tried to find a defensive home for him, as Green has played center field, left field, third base and second base, where he's been exclusively in 2013 with Triple-A Sacramento.
With very little production out of the second base spot in the majors, the A's are giving Green a long look at the position with Jemile Weeks making more starts at shortstop in order to accommodate him. The 25-year-old Green, who has an .822 OPS and is hitting .340 (18-for-53) in June, could give Oakland a big boost on offense.
If the A's think he can be at least an adequate defender, expect him to get a chance very soon.
The Mariners didn't give infielder Nick Franklin a shot in the majors until they were ready to send struggling second baseman Dustin Ackley to the minors, even though they were getting almost zero production out of the shortstop position.
Ackley's minor league stint was expected to be short, however, and he's already making a strong case for a return. So now they've moved him to left field to "provide more options", according to general manager Jack Zduriencik.
You want to know the truth? The Mariners don't think Franklin is a shortstop. He's found his home at second base and will very likely remain there for the next several years. Ackley will likely return as an outfielder, and shortstop could belong to Brad Miller very soon.
The 23-year-old Miller, who has the defensive ability to be a major league shortstop, hasn't stopped hitting since the M's took him in the second round of the 2011 draft. In 59 games this season between Triple-A and Double-A, Miller is hitting .313 with nine homers, 30 walks and 43 strikeouts.
Will Myers has been on fire over the last few weeks with 29 hits in his last 81 at-bats (.358 BA), including nine homers and 29 runs batted in.
If this sounds familiar, it's because the 22-year-old has already proven that Triple-A pitching isn't much of a challenge for him. He had a .937 OPS in 99 Triple-A games in 2012 while he was still with the Royals.
With his major league debut likely weeks away, the Rays will likely be trying to figure out how to get him regular at-bats and who will be the odd man out. Kelly Johnson and Luke Scott are both slumping badly so the promotion is becoming closer and closer to a reality.
One of the rare pitching prospects with No.1 starter potential, Taijuan Walker is getting closer to joining one of the few true aces in the majors.
Walker could join Seattle ace Felix Hernandez and Hisashi Iwakuma, one of the best 1-2 punches in the league, in the Mariners' rotation soon if he continues to dominate in Double-A.
In his last 10 starts, the 20-year-old has seven starts where he has pitched at least six innings, allowed one earned run or less, four hits or less and struck out at least six. If the Mariners continues to struggle, they could move towards an all-out youth movement with Mike Zunino, Nick Franklin and Brad Miller in the everyday lineup and Walker pitching every fifth day until they decide to shut him down for the year.
Zack Wheeler's impending major league debut has been discussed so often that you'd think he was pitching a lot better than his 4.14 ERA would indicate.
But Triple-A Las Vegas in the Pacific Coast League might be one of the least pitcher-friendly environments around so it's not all that bad.
The 23-year-old hasn't dominated, but his peripherals are strong (63 IP, 60 H, 25 BB, 66 K) and his repertoire of pitches is even stronger. He may not be Matt Harvey—no one thought that Harvey would emerge as a big league ace, including Harvey— but he has top-of-the-rotation potential and shouldn't be too far away from reaching that potential.
A 2014 rotation of Harvey, Wheeler, Jon Niese and Double-A prospect Rafael Montero should help Mets fans erase the nightmare of a season they're currently enduring.