Sometimes, a player is so good so soon that a team's hand is forced.
Sometimes, a player is just that ready.
While counting down to Opening Day on Thursday, MLB.com is identifying Five To Watch in various categories -- from big names looking to get healthy, to big question marks looking to get their acts together.
Here are five young standouts who seem painstakingly close to debuting in the Majors, five players we can't wait to see:
Brandon Belt, 1B, Giants
Little doubt remains about whether Belt is ready to be an everyday Major Leaguer. The question is whether he'll immediately do so for the reigning World Series champions.
That decision will rest on the lap of manager Bruce Bochy, whose lineup is in a relative state of flux because outfielder Cody Ross will start the season on the disabled list with a calf injury. But Belt, a 22-year-old with a sweet lefty swing, slick glove and solid makeup, is too good to serve as a mere stopgap. He'll be up only when he's guaranteed to play every day.
Opening Day or not, that reality doesn't seem very far away.
Bryce Harper, RF, Nationals
Considering how mature he looks waving a bat, it's hard to believe that Harper won't even be 19 -- 19! -- until October and hasn't played in a Minor League game yet.
But no matter how much power he has and how well he projects, there's no need to rush somebody that young and inexperienced. So on March 12, after Harper hit .389 in 18 Grapefruit League at-bats, the Nationals did the expected and sent the lefty basher to Minor League camp -- not because he didn't impress, but because there are still things that he must experience.
"Hopefully," Harper said, "I will get a September callup or something like that -- maybe even earlier."
With bated breath, we shall wait.
Mike Moustakas, 3B, Royals
Moustakas, a stout 22-year-old with a dangerous lefty bat, came into his second Spring Training with a chance -- albeit a distant one -- to win the starting third-base job, but he didn't really overwhelm offensively in his small sample size.
Moustakas' bat is in no way a problem, however. He has proven that all throughout his Minor League career. What Moustakas admittedly must work on before he's ready for Major League stardom is defense.
"That's one of the areas of my game that needs a lot of work," he said after being cut on March 16, "so I've got to go out there every day and get better somehow."
Michael Pineda, RHP, Mariners
Pineda is an amazing physical specimen -- 6-foot-7, 260 pounds -- with a fastball that sits consistently in the upper-90s, good but still developing offspeed stuff and pretty precise control despite an electric repertoire.
The 22-year-old impressed this spring, enough so that the Mariners named him their No. 5 starter. This season he'll look to develop an effective offspeed pitch against left-handed hitters, and the Mariners will probably monitor his innings after he wore down a bit toward the end last year.
Soon enough, Pineda figures to give the Mariners a lethal one-two punch with Felix Hernandez.
Mike Trout, CF, Angels
MLB.com's No. 1-ranked prospect has blazing speed, a nice swing, a dynamic glove and, perhaps most of all, a sparkling baseball IQ -- which is impressive when you consider that he's only 19.
"This guy's as far advanced as anybody over the past few generations we've seen," Angels manager Mike Scioscia said. "He's got a great head."
Trout's patience at the plate has been compared to that of Bobby Abreu; his defense to that Torii Hunter; his speed on the basepaths to former Angel Chone Figgins.
For now, Trout will play in Double-A. Soon, he'll put those tools on full display at the big league level.
More future stars coming soon to a Major League roster near you: Braves first baseman Freddie Freeman, Mariners second baseman Dustin Ackley, Orioles left-hander Zach Britton, Indians third baseman Lonnie Chisenhall, Royals first baseman Eric Hosmer, Blue Jays third baseman Brett Lawrie and Yankees catcher Jesus Montero.