With the hype machine firing on all cylinders, Yankee phenom Manny Banuelos took the mound on Monday night in a nationally televised game against the big-league lineup of the Boston Red Sox just one day after his 20th birthday. While he struggled with his command at times, he was otherwise worthy of the praise he's been receiving, as he showcased well above-average velocity and an outstanding changeup that generated silly-looking swings from two of Boston's best hitters, Dustin Pedroia and Kevin Youkilis. One scout watching the game said he was tempted to put an 80—the highest possible score—on the pitch.

With the Yankee rotation in more than a bit of flux, the calls from fans for Banuelos to be part of the immediate solution continue. He'll make at least one more appearance with the big-league team, likely on Saturday, but he's going to the minors after that, and it's the right decision for the Yankees' long-term picture.

Twenty-year-old starting pitchers in the big leagues are a rarity, but having a player like Banuelos, who has made just three starts above A-ball, in the big leagues would be nearly unprecedented. Just 17 pitchers this decade have come up as starters prior to their 21st birthday, and the one constant among them was a full workload the previous year, as they averaged more than 140 innings in the year prior to their debut, with all 17 pitching at least 100 frames. In addition, only three of the seventeen, CC Sabathia (2001), Jeremy Bonderman (2003), and Rick Porcello (2009) opened their debut year in the majors, with the remaining 14 averaging more than 100 minor-league innings in the season they first got the call.

Make no mistake about it, Banuelos could at the very least hold his own in the big leagues right now, but the real question revolves around the question of how long he could do it. He's never thrown more than 109 innings in any one season, and last year he threw just 65 after an emergency appendectomy delayed the beginning of his season until June. With many teams believing in no more than a 50 percent increase in workload as a basic rule, that would line Banuelos up for 100 frames this year, and even a plan with fewer limitations would still likely keep him under 125. "He has everything he needs to succeed in the big leagues except the ability to handle the workload," said one AL executive. "They need to stretch him out, get him 100 safe innings, and medical people will tell you that if you jump his innings in a big-league environment, that would be an even bigger risk."

That means that even if the Yankees opened the year with Banuelos in their rotation, they'd almost certainly be unable to finish it with him, or have him available for the all-important post-season. One National League executive saw breaking camp with Banuelos as a potential public-relations problem no matter how he pitched. "If he fails, then they're losing games and they've rushed him, and it could hurt him long-term in terms of confidence," the exec explained. "But what if he starts off gangbusters and he's 9-2 in July, has pitched 100 innings and they're batting Boston in the American League East?" he asked. "Are they going to shut him down? How do you think that will go over with the fans and the New York press? I bet there was a part of Yankees brass that was hoping he got tagged on Monday so they could just treat him like a normal prospect." The American League executive mostly agreed, but also admitted to what are at times special circumstances in the Big Apple. "Every other team in baseball would say we're going to build this guy up in the minors, but the Yankees always need to win now, and he's their best guy," he explained. "They are not a team that ever likes to go with placeholders."

Opening the year at Double-A Trenton is best for both the Yankees and Banuelos. His innings and pitch counts can become the core of his development, without any concern for the score or the standings, and he can still work on harnessing what is already a good arsenal, but is still unquestionably a work in progress. While Joe Girardi continues to to not rule anything out, Yankees brass insists he's going to the minors, with a focus on his long-term development. "There are few guys that can bypass Triple-A, and even fewer than can all but skip Double-A," said Mark Newman, the Yankees' Senior Vice President of Baseball Operations. "We understand the excitement, and when we sit behind the net and watch him, we get excited too, but we have to be objective and rational and he still has things to do in terms of pitch development."

In the end, the question of Banuelos' readiness is less about the prospect and more about the failures of the Yankees to shore up their rotation in the offseason by putting all their eggs in the baskets of Cliff Lee and the anticipated return of Andy Pettitte. "If A.J. Burnett is their number five starter, everyone is happy in Yankees land," said the National League executive. "If they signed Lee; if Pettitte came back, we wouldn't be having this conversation. Just because the Yankees [screwed] up this off-season doesn't mean they should sacrifice this kid in the process."

A version of this story originally appeared on ESPN Insider Insider.