For all that is uncertain this time of year -- which teams are or aren't selling, or which players are or aren't on the trading block -- one thing is clear when it comes to the Mets: If they wind up shipping out any pieces, general manager Sandy Alderson's preference in a return is Major League-ready players. Enough with the long-term rebuilding.

"That in and of itself militates against a [non-waiver Trade] Deadline deal," Alderson said during the club's last homestand before the All-Star break. "If you're making deals at the Deadline with 'contenders,' they're not anxious to give up Major League-ready players or Major League players. But I think that's actually been our mindset for a while. The question is, what can you get back that's Major League ready?"

So if baseball executives have to adapt, Alderson needs to look back no further than 11 months for a potential solution. A late-August deal sent catcher John Buck and outfielder Marlon Byrd to Pittsburgh for reliever Vic Black and Minor League second baseman Dilson Herrera, a deal made sense for both sides. It worked out particularly well for the Pirates, whose big get -- Byrd -- hit well for them during their playoff push.

The next two weeks until the non-waiver Trade Deadline, Alderson could wind up pointing to last year's deal as a starting point if and when his phone starts to ring about any number of players he could make available. The template: New York sends Team X a veteran or two who could be of immediate and immense value to that club, in exchange for a near-ready Major League piece as well as a prospect a little further away.

"It is a framework for what clubs are looking for," Alderson said. "Something for now, something for later."

That approach worked out quite well for the Mets last time. Less than a year removed from the Byrd trade, Black has become a crucial late-inning arm for a Mets bullpen that has been very strong since stabilizing in May, while Herrera's stock has risen with Double-A Binghamton.

On the surface, Black's growth seems simple: He got a shot. After feeling ready for The Show but getting no more than a 10-day cup of coffee with the Pirates, Black joined the Mets' bullpen immediately -- then pitched in three straight games for the first time, against a sequence of batters he can recall immediately. Black made it to the Majors for good at the end of May after opening the season with Triple-A Las Vegas.

Black still walks a few too many hitters, though that's gotten better since returning to the bigs, and he's posted a 1.69 ERA while striking out nearly a batter per inning. The most significant sign of growth, according to Black, is that he can recognize when he isn't feeling 100 percent on a given day and adjust accordingly.

"At that time [of the trade], I trusted who I was at a pitcher, but I think even more so now," Black said. "Some days I warm up in the 'pen, and it's just not as easy to warm up. I know what I got today, so I can't go out trying to do what I did yesterday. … You get outs. It doesn't matter if they come on three Ks or you get three warning track pop flies. They're outs, and it's going to happen."

The bigger wild card -- and maybe the bigger prize, ultimately -- is Herrera. He's only 20, only 5-foot-10 and only 150 pounds, but he's arguably the organization's most well-rounded middle-infield prospect. MLB.com's 2014 Prospect Watch ranks him as No. 9 in the Mets' system.

After Herrera hit .307/.355/.410 during the first half for Class A Advanced St. Lucie, the Mets promoted him in mid-June to Binghamton, where he's been even better. He owns a .326/.398/.495 slash line through 23 games in Double-A, and while that's a small sample size, it is noteworthy because Herrera did not experience any sort of adjustment period typical of a younger player moving up a level.

"He's aggressive. He's always hunting for that fastball early in the count," Binghamton manager Pedro Lopez said late last month. "And if he gets it and he feels like it's good for him to drive, he goes after that."

Added Alderson: "He's starting to control the strike zone a little more in Binghamton. He's shown surprising power for his size and age. … His athleticism, his body type [allows him to hit for power]. He's aggressive and generates a lot of bat speed."

For Herrera, who has been generally successful at the plate since signing with Pittsburgh as a 16-year-old out of Colombia in 2010, the most exciting development might be that he has gotten to play shortstop again. He signed his first pro contract as a shortstop, but when he showed up to play, the Pirates stuck him at third base, then second, where he remained until this spring. Herrera doesn't know why he never got a chance at his natural position.

"That happens a lot," Alderson said. "Guys get pigeon-holed without good reason."

To amend that, about one-third of Herrera's time this season has come at short, where he continues to take grounders regularly.

"If you play short, you can play anywhere on the infield," Herrera said, with Binghamton hitting coach Luis Rivera serving as translator. "I like shortstop more, because it's harder to play. I move my feet more and take charge of more stuff. It's more responsibility to play short."

Where Herrera ends up long-term is up to the player and whether he can handle the greater responsibility, according to Alderson. Lopez said Herrera's future hinges on his arm, which right now isn't quite up to par for shortstop, although his range as a second baseman is excellent. Herrera sees himself as a shortstop.

It's at least worth a shot.

"See what's there. Where the potential doesn't exist, the experiment doesn't last very long," Alderson said. "Ultimately, from my standpoint, the bat plays. If the guy can hit, let's find him a position."

And, to be sure, the bat does play. Aside from the increased power, Herrera has also cut down his strikeout rate from nearly one in four plate appearances last season to just 16 percent of chances in 2014.

"Usually when you see kids his age getting to this point, the tendency seems to be some guys being more pull hitters than anything else," Lopez said. "What he does is have plate discipline and an ability to drive the ball the other way. That's what makes him successful."

So if and when Herrera makes it to the Majors, remember Byrd. Remember the "something for later."