Xander Bogaerts has passed every test put in front of him. He's hit in Single A and Double A, and now he's hitting in Triple-A. He's always been one of the youngest players at each level and has excelled everywhere he's been. His physical tools and (to use scout-speak) "makeup" grade out very highly. He is the total package, and that's why he's considered one of the best prospects in baseball and a future star.

In a piece for Boston.com calling for his promotion to the big leagues, the excellent Chad Finn wrote this: "Bogaerts is a special prospect, and if anyone tells you that, oh, Andy Marte was too and look how that turned out, disregard their opinion for they haven't done their homework. He is as can't-miss as can't-miss gets."

He is, as Mr. Finn writes, as can't-miss as can't-miss gets. I read that and thought, yes, that is exactly how I feel. But now I wonder if I'm wrong. There is no such thing as a can't-miss prospect. Even the people who evaluate baseball prospects for a living get it wrong.

So many prospects fail that you'd think grading baseball players was more difficult than actually playing baseball. Maybe it is! Prospects fail for many reasons. Becoming a major league baseball player, let alone a star, involves the development of so many skills -- and, to be blunt, so much luck -- that guessing years in advance which players will do it successfully amounts to, well, educated guess work. Some players are likely to develop certain skills but just never do. Some guys have holes in their game that get exploited by better pitching or hitting as they make their way up the minor league ladder. Some guys get fat, some guys don't try hard enough, and some guys get hurt. Lots and lots of guys get hurt.

Look back at the 1st round of any draft -- literally, pick any single draft you want -- and you will find that half of the guys picked, half of all those 1st round draft picks with the shiny star on their chests that comes with that designation, never even made it to the major leagues. These were highly graded guys with lustrous tools who, in almost every case, produced well above average before getting drafted … and then turned into nothing.

Of course, there are many differences between a player fresh out of the draft and Xander Bogaerts, who has advanced all the way to Triple A. And yet, even success in Triple A and all the tools in the world are no guarantee of success.

Just as the road to the majors is littered with former prospects, so too is it filled with scouting, development and analysis mistakes. Two players stand out to me when thinking this through. The first is Orioles catcher Matt Wieters. Wieters was first ranked prospect by Baseball America in before the 2009 season. He was picked 5th overall and not 1st, because he was thought to be too expensive by the teams with the first four picks. In the minors, he posted an OPS over 1.000 in both Single A and Double A. It was thought by some that he would step into the big leagues and immediately become the best hitting catcher in the game. It didn't happen. Wieters has turned into a fine player, but it's mostly because he is an excellent defensive catcher, and less so because he's a good-for-a-catcher but not-great hitter.

It's difficult to say for certain that we all missed on Wieters -- he's still just 27, and catchers develop later than other prospects -- but to date, he hasn't been the star his scouting reports and minor league stats projected him to be. In retrospect, what we got wrong about Matt Wieters was that we placed too much stock in his minor league stats. Yes, he destroyed minor league pitching, but he did it as a 22- and 23-year-old out of college. When he got to Triple A, his stats dropped considerably, and that trend continued in the majors. A scout probably could pinpoint the exact reasons Wieters hasn't translated his minor league successes to the majors, and it probably would be something like this: Wieters already had fully developed as a hitter by the time he reached Double A, and as such, he could take full advantage of less-developed minor league pitchers. If you put an average major league hitter in Double A, he'd look like the best player in the league, but put him back in the majors and he's just average again. That is Matt Wieters.

The other guy I thought of was Hanley Ramirez. Ramirez was always well regarded by scouts, but the stats guys looked at him with skepticism. He never put up a great full season in the minors, and he seemed disinterested at times. Scouts insisted he had the tools and skills to be a star in the majors. Stat guys (I consider myself one of them) disagreed. Turns out the scouts were right. Sometimes players don't post good numbers for reasons other than that they can't. Sometimes it isn't that the skills aren't there, it's that a player simply hasn't learned how to use them yet.

Finally, let's look at Mr. Finn's example, Andy Marte. From 2003 through 2006, Andy Marte was a top-40 prospect in baseball according to Baseball America. In 2004, Marte was ranked 9th, behind Joe Mauer and Felix Hernandez and a bunch of guys you probably haven't heard of since 2004. Baseball America published a quote next to each prospect on their Top 25 list. Marte's comment quoted then Birmingham manager Razor Shines, who said, "There's nothing not to like about Andy Marte. He's an outstanding defender with a chance to be an impact player offensively."

The 2005 Baseball Prospectus Annual listed Marte as the best prospect in baseball and provided the following: "The best prospect in baseball and a future superstar. As a 20-year-old toiling in the mostly hitter-unfriendly Southern League, Marte hit .269/.364/.525. In only 387 at-bats, he smacked 52 extra-base hits. He's got monstrous power and a broad base of hitting skills."

Andy Marte spent parts of six seasons in the major leagues and hit .218/.277/.358. That's bad. Both Baseball Reference and Baseball Prospectus have Marte as a below-replacement-level player for his career, meaning he has been worse than a guy you might pluck for free from a Triple A roster. Andy Marte has been a bust, and everyone was wrong about him. But why?

As Baseball Prospectus noted, Marte hit extremely well in Double A, as a 20-year-old, and hit just as well in Triple-A the next season. I'm not an expert in the run environments that Marte played in, so maybe there is huge difference between the Sally League and the International League -- or between those and the rest of minor league baseball -- but if that were the case, wouldn't someone have noted it when they ranked Marte?

The knock on Marte, at least in retrospect, seems to be that he never developed his ability to make enough contact, something that got exploited in the major leagues. Also, his defense was graded very highly, but since he couldn't maintain an on-base percentage above .300 in the majors, it didn't particularly matter. In the end, we missed on Marte, but we didn't miss anything particularly massive. It seems to be a bunch of small things that either didn't develop, never improved or even got worse. But that's all in retrospect. It's much harder to look at the 20-year-old Marte and say, that guy won't ever amount to anything. Even if you downgrade the hype, at the time he still looked very good. He still looked like an above-average major leaguer.

Some say you can't trust an ex-Braves prospect, meaning that if the Braves are willing to deal a player, then there must be something wrong with him. But in Marte's case, look at the teams who dealt for him: the Cleveland Indians and Boston Red Sox, two of the smarter teams, both adept at statistical analysis and scouting and, most importantly, at meshing the two together. If anything negative can be attached to Marte through being dealt from Atlanta, surely being acquired by Cleveland and Boston can erase it.

We've made progress in how we scout and rank players in the 10-plus years since Andy Marte emerged as a prospect. We have a better grasp of run environments, the meaning of player age and tool development. We know enough not to fly off the handle when a 22-year-old has a great year at Double-A. We know to place more stock in the scouts when a super-talented player produces well below his capacity at a young age in the mid-minors. In short, we're learning why players succeed in the minors or don't, and what that might mean or, alternately, what it might not mean for their future in the major leagues.

As for Bogaerts, he doesn't really fall into any of those holes. He hits for average, he takes walks, he hits for power, and he doesn't have holes in his swing that major league pitchers will be able to exploit (for example, an inability to hit a certain pitch). He isn't Andy Marte's skill set, he isn't Matt Wieters' minor league numbers, and he isn't, for better or worse, Hanley Ramirez's disinterest. But he could be something different. To paraphrase Mr. Finn, Xander Bogaerts is as can't-miss as can't-miss gets, but sometimes can't-miss misses anyway.