So Fernando Martinez is off to the Astros, cut from the Mets’ 40-man roster to make room for Ronny Cedeno and his career .286 on-base percentage, joining Lastings Milledge and the Alexes Ochoa and Escobar in a long line of ballyhooed Mets outfield prospects to ultimately provide the team little more than a handful of underwhelming at-bats plus Rich Becker, Ryan Church and some fraction of one-and-a-half pitiful seasons’ worth of Robbie Alomar.

In Martinez’s case, the hindsight is now crystal clear: They should have traded him for Dan Haren or CC Sabathia. They should have seen and understood his obvious physical limitations instead of stubbornly clinging to his youth and promise despite his general lack of meaningful production at any Minor League level.

That’s true, really. Based on the way it all panned out for Martinez with the Mets, they absolutely should have traded him when he still maintained some of the value that came with the Teenage Hitting Machine hype, regardless of what so many of us believed then and probably still believe now about the importance of developing players from within. And we can reasonably debate whether Martinez, at 23, was the sensible guy to cut from a roster that still includes Armando Rodriguez, D.J. Carrasco and Jeremy Hefner, but there’s really no arguing that the Mets of 2007-2011 wouldn’t have been better off parting with Martinez at some time sooner than Jan. 11, 2012.

It’s… well, it’s disappointing, for one thing.

But there are some lessons here regardless, and they are absolutely not that every team should trade its much-hyped prospects for available veteran help — though Martinez’s case will inevitably be cited to make that argument at some point in the not-too-distant future.

His fall from stature instead underscores, I think — and once again, really — the enormous challenge of scouting, developing and understanding young talent that is endeavored by teams, the baseball media and fans alike.

Using Baseball America’s preseason rankings, Grant Brisbee painted a heartbreaking picture of Martinez’s accelerating decline over the past four years. Understandably unstated in the post is that none of Ruben Tejada, Daniel Murphy, Lucas Duda or Dillon Gee ever ranked among Baseball America’s Top 100 and all a) have now inarguably provided the Mets more than Fernando Martinez ever will and b) are currently penciled or inked into starting roles for the 2012 Mets, for better or worse.

Which is not to diminish the exhaustive work done by Baseball America or any other prospecting outlet, only to qualify it. Those rankings are based in part on the players’ upside, and certainly none of the young Mets appear likely to ever be as good as people thought Martinez might have someday been, back when he was still a Teenage Hitting Machine.

Any reasonable Minor League writer will admit that he’s dealing in a ton of uncertainty — they’re called “prospects,” after all. Players develop at various speeds in various ways, and there are hundreds of possible routes to a successful big-league career. Sometimes 19-year-old prodigies develop arthritis and flame out, and sometimes 24-year-old slap-hitters start crushing Double-A pitching and never stop.

That is a long-winded way of saying: It’s best not to rush to rule anyone out or in.

It’s not to say we shouldn’t bother paying attention. Even for all my most-prospects-suck crotchetiness, I still gobble up nearly every year-end ranking of Mets prospects I can find and pore over stats from the team’s low Minors looking for diamonds in the rough. It’s fun, and when the team’s immediate big-league chances look gloomy, it’s a great way to maintain hope for sunnier days down the road. But I would caution against putting too much faith in any list or getting too worked up over rankings. (I tend to trust Kevin Goldstein and our own Toby Hyde most on Mets prospects, for whatever it’s worth.)

Back to the now-departed Fernanchise: I hate to be this guy again, but I think the other lesson or reminder or general item of sadness inherent in the move is the human aspect to it.

And maybe I shouldn’t feel sorry for a guy who got more money for playing baseball at 16 than I likely ever will for anything in my life, but for whatever reason the image of Martinez that stands out in my memory is seeing him leaving the Mets’ Spring Training clubhouse in jeans and a t-shirt looking very much like the college-aged kid he was: certainly athletic, but perhaps a bit soft in the belly. And I remember thinking about the grumblings I’d heard that week about his work ethic, and then thinking about what people would have grumbled about my work ethic (and belly) at 22 (or ever) if anyone outside my family cared.

Martinez is still only 23, so in all likelihood there’s plenty of time for him in baseball and everything. Maybe he gets an opportunity in Houston and hits like Ted Williams, or at least like Carlos Lee, and enjoys a long, successful career in the Majors. Or maybe he doesn’t, but he’s smart and resourceful enough to find a gainful and satisfying way to occupy the rest of his years, inside or outside the game.

And though I’d be hard-pressed to argue there are many better ways to spend your late teens and early 20s than playing baseball — or more accurately, in Martinez’s case, rehabbing for baseball and “resuming baseball activities” — even with all the long bus rides and crappy hotel rooms and cheap meals intrinsic to Minor League life, you’ll never convince me it can’t be strange and at least a little bit sad to wake up at 23 facing the real possibility that the goal you’ve been pursuing since 16 may be unobtainable due in part to physical factors largely beyond your control, and that all you’ve heard about your potential from the crowds gathering around your batting-practice sessions could very well amount to little more than 131 Major League at-bats and a hell of a lot of fuss.