Less than 48 hours after Drew Pomeranz played in his first All-Star Game , the Padres demonstrated a classic example of selling high, trading the left-hander to the Boston Red Sox for top pitching prospect Anderson Espinoza. The move, officially completed Thursday night, furthered San Diego's rebuilding process while adding one of the minors' brightest young talents to the farm system.

Pomeranz, 27, had seen his value skyrocket in his first season with the Padres, who, in a pitching-thin market, dealt him at his peak. Thursday represented the culmination of a chain of events that began in December, when General Manager A.J. Preller sent Yonder Alonso and Marc Rzepczynski to Oakland for a package featuring Pomeranz, a former first-round draft pick who'd yet to find consistency.

Things clicked in San Diego, where Pomeranz went 8-7 with a 2.47 ERA over 17 starts. His .184 opponents' batting average was the best in the National League , while his strikeout rate (10.1 per nine innings) was the seventh-highest.

"Not an easy guy to deal," Preller said. "Any time you have a left-handed starter that's performed the way he has, you have to feel very good about the return you're getting. ... We felt like we were getting a premium guy and someone who's been close to untouchable last year."

Espinoza, 18, was ranked 15th on Baseball America's midseason top-100 prospects list. As the youngest pitcher in the Sally League this season, the right-hander posted a 4.38 ERA in 17 starts for low Single-A Greenville. The 6-foot Venezuelan has been compared, probably unfairly, to Pedro Martinez, but his velocity (already in the mid-90s, will touch 99) and advanced secondary pitches (curveball, change-up) are those of a potential star.

The Red Sox's offer stood out. Preller said "quite a few teams" expressed interest in Pomeranz, and a source confirmed about 10 clubs inquired about the left-hander's availability.

"He was a high-profile July 2 sign (the Red Sox paid Espinoza $1.8 million in 2014) and pretty quickly lived up to the hype," Preller said of Espinoza. "Not ultra-tall, but we do think there's some physicality there to the body. He's filled out, started to put on weight. Our scouts talked about how easy his delivery is, how easy he does things. He throw strikes. As we looked at it and evaluated prospects and pitchers in the minor leagues, he was pretty much at the top of our board over the last year or so."

On a conference call with reporters, Dave Dombrowski , Boston's president of baseball operations, said: "I'd rather trade three other type guys than Anderson, but that wasn't appealing to San Diego."

In return, the Red Sox received Pomeranz, who is making only $1.35 million this year and was especially attractive because he is under club control for two more seasons. The Padres decided to trade the All-Star largely due to timing; currently in fourth place, the club is unlikely to contend before 2019.

Drew Pomeranz posts his thanks pic.twitter.com/WTxv4o7aIe — Drew Pomeranz (@DrewPomeranz) July 15, 2016

"Best case scenario, obviously you're contending and in first place and Drew's pitching in game one or two of the playoffs," Preller said, "but we mentioned it all along; we're trying to build, acquire and add to a talent base. It's a good scenario for us to get one of the top 15, 20 prospects in baseball and a guy, long-term, we think is going to be a big asset."

Espinoza instantly becomes the Padres' No. 1 prospect, ahead of center fielder Manuel Margot, also acquired from Dombrowski and the Red Sox. His acquisition continues a recent trend for Preller, who last month used 10 of his first 12 draft selections on pitchers. The GM has since traded closer Fernando Rodney for right-handed prospect Chris Paddack and signed Cuban lefty Adrian Morejon for a club-record bonus of $11 million.

"It takes a lot of pitching prospects to end up with a championship-type pitching staff," Preller said. "There's huge value in depth and numbers. ... I think in a pretty short period of time we've gone from an organization with a handful of guys to now, every day when you look up, there's a pitcher on the mound who has a chance to be impactful."

Many of those arms will reside in the lower minors for at least the next year, the hope being that the Padres will eventually field one of the big leagues' more formidable pitching staffs.

In the meantime, the current rotation is down to Andrew Cashner , Colin Rea, Christian Friedrich and Luis Perdomo — a mix of inexperience and, in Cashner's case, unfulfilled potential. Preller said Manager Andy Green and pitching coach Darren Balsley would determine how to fill the void created by Pomeranz's departure, but he did mention reliever Paul Clemens and minor leaguers Edwin Jackson and Michael Kelly as options.

The Padres, who began this year's sell-off by dealing James Shields in early June, retain a number of trade candidates. They include Cashner, catcher Derek Norris , outfielder Melvin Upton Jr. and third baseman Yangervis Solarte. Executives around baseball believe San Diego will have difficulty trying to move outfielder Matt Kemp, who is under contract through 2019. The non-waiver trade deadline is Aug. 1.

View the Video Drew Pomeranz on getting another shot

"I do think we have guys that are of interest to other clubs," Preller said. "You listen on everything, but we've kind of shown we're going to set a value for each player, and if teams see it that way and give the right value, we're going to be prepared to trade. But if not, you're going to hold on to guys. I think it's going to be on an individual basis and we'll get more of a feel for it in the next couple weeks."

For Pomeranz, being traded is nothing new. The ascendant lefty will make the Red Sox his fifth organization.

"The first time I got traded, I was in the bullpen warming up for a game in Double-A and got called back in and got traded," Pomeranz said this week. "So that was probably the craziest it could be. Once I got traded the next time, it got a little easier, and then I get traded the next time — it’s just part of it. It’s part of the game."