Less than 48 hours after last year's All-Star Game concluded at Petco Park, the host Padres agreed on a trade that sent left-hander Thomas Pomeranz to the Red Sox.

Translation: The first domino of this July 31 non-waiver Trade Deadline could tumble at any moment.

Here's a prospectus on the position-player market, with less than three weeks remaining before the Deadline.

Teams on the bubble -- specifically the Blue Jays, Angels, Mariners, Rangers and Cardinals -- are considered sellers here, in order to provide the most comprehensive outlook. If those clubs play well coming out of the All-Star break, their trade candidates will recede from the list.

Catchers

Top names:Alex Avila, Jonathan Lucroy , Tyler Flowers, Nick Hundley, Carlos Ruiz , A.J. Ellis, Chris Stewart

Avila is expected to be the most popular name in this market. The postseason veteran has shown he's comfortable in a backup role, but he is hitting like an All-Star now (his .958 OPS leads all Major Leaguers who caught at least 40 games in the first half). Lucroy is a bounce-back candidate after struggling in the first half of his contract year; the Rangers are willing to move him, according to Ken Rosenthal of FOX Sports.

Flowers is having a career offensive year (.838 OPS), and the Braves hold an attractive $4 million club option on him for 2018. Atlanta general manager John Coppolella has little incentive to move Flowers, but he's made unexpected moves before. The Marlins are unlikely to move J.T. Realmuto while waiting for the franchise to be sold.

Teams shopping: Cubs, Rockies, Nationals

The Cubs are known to have interest in Avila, following the abrupt dismissal of Miguel Montero . The Rockies, short on postseason experience, would love to add a veteran backstop who can help guide the team toward its first postseason berth since 2009.

The Nationals have the worst OPS behind the plate in the National League, although Matt Wieters has earned positive reviews for his handling of the pitching staff.

First basemen

Top names: Yonder Alonso , Justin Bour , Tommy Joseph, Brandon Belt , Jose Abreu , Mike Napoli

Sign of the homer-happy times: 16 first basemen have hit 15 or more home runs already this season, an indication that there's ample supply of sluggers at the position ... and relatively few teams that need more power there.

Alonso is the likeliest candidate to be dealt, coming off his first career All-Star appearance; he will be a free agent after the season, and the A's aren't close enough to a new ballpark that a large contract extension is realistic. Joseph is an under-the-radar candidate, with 24-year-old Rhys Hoskins -- who started at first base for Team USA in the Futures Game -- ready at Triple-A.

Teams shopping: Mariners, Yankees, Angels

The three teams listed above rank 28th, 29th and 30th among all Major League teams in OPS at first base. Alonso makes the most sense for the Yankees, who are certain buyers. The Mariners and Angels will be more interested in long-term assets, since they're on the fringes of a crowded American League Wild Card picture; Belt is a fit for either of them, if the Giants decide on a more dramatic reshaping of their roster.

Second basemen

Top names: Ian Kinsler , Dee Gordon, Joe Panik, Brandon Phillips

Kinsler was a popular name on the offseason trade market, but the circumstances have changed since then: The Dodgers found a steady player at the position in John Forsythe , Kinsler is having the worst offensive season of his Major League career (.710 OPS), and relatively few teams need help at the position.

The Marlins aren't engaging on many of their big-name position players, but Gordon is an apparent exception; Jon Heyman of FanRag Sports reported that the Angels, Blue Jays and Royals "have at least mentioned" Gordon.

Teams shopping: Angels, Rays, Blue Jays, Indians

The Blue Jays remain enamored with Devon Travis as a player and person, but he's missed so much time due to multiple injuries that they have little choice but to seek other options. Gordon offers the speed Angels manager Mike Scioscia covets. The Indians are included because of Jason Kipnis ' injury-plagued season; he was placed on the disabled list again Sunday.

Third basemen

Top names:Josh Donaldson, Todd Frazier , Yunel Escobar , Wilmer Flores , Maikel Franco , David Freese

A Donaldson trade would qualify as a blockbuster, and the Giants and Cardinals both have interest. That said, it's still unclear if the Blue Jays are willing to engage in talks about him. A Frazier trade could lead to reshuffling on the White Sox infield and the eventual promotion of Yoan Moncada , who has played strictly second base in the Minors this year.

Teams shopping: Giants, Red Sox, Yankees, Cardinals

Third base is the site of considerable consternation at Fenway Park: Travis Shaw stars in Milwaukee, while Pablo Sandoval remains on Boston's disabled list with a .212 batting average. Prospect Rafael Devers isn't quite ready. The Red Sox's best option could be to trade for a rental (Frazier) or utility player (Martin Prado) who moves around the diamond once Devers is ready. (The Red Sox have interest in Prado, according to USA Today's Bob Nightengale.)

Shortstops

Top names:Zack Cozart, Jordy Mercer , Jose Iglesias , Asdrubal Cabrera , Erick Aybar

Cozart is a classic trade candidate: He's having an All-Star season, in a contract year, for a rebuilding team. (A contract extension for Cozart remains possible but is probably unlikely.) Mercer has been a quietly consistent part of the Pirates' core through the franchise's renaissance; yet the fact that he'll be a free agent after 2018 means he's available on some level, given the club's economic circumstances.

Teams shopping: Nationals, Cardinals, Twins

The shortstop market could remain quiet this month. The Nationals' biggest priority is the bullpen, although it's conceivable the Reds could package Cozart and closer Raisel Iglesias to obtain a monster return from Washington. The Cardinals need a long-term solution; Iglesias could be the best available option, given his defensive ability. Iglesias, though, will be eligible for free agency after next year.

Utility players

Top names:Josh Harrison, Jedd Gyorko , Jed Lowrie , Jose Pirela , Eduardo Nunez , Martin Prado , Cliff Pennington, Adam Rosales , Danny Espinosa

The Cardinals aren't eager to move Gyorko, who in many respects has been their steadiest offensive player, but they could sell high if the offers are overwhelming. (St. Louis' infield needs a reboot, with an emphasis on defense, so virtually every idea is on the table.) Lowrie (.805 OPS) is enjoying the best and healthiest season of his career, in what is likely the last year of his second tenure in Oakland.

Teams shopping: Everyone

OK, perhaps not everyone. But you get the idea. Serious World Series contenders often look to upgrade their bench with defensive versatility and/or postseason experience. Harrison is an ideal fit for the Angels, Blue Jays, Indians, Yankees, Red Sox, Giants ... and probably a few other teams, too. Lowrie's versatility around the infield should enhance his appeal to the Yankees.

Center fielders

Top names: Andrew McCutchen , Jarrod Dyson , Denard Span , Carlos Gomez , Cameron Maybin

McCutchen is playing center field every day and has a 1.226 OPS since Clint Hurdle dropped him to the No. 6 spot on May 26. McCutchen has since moved back up to third -- and has kept hitting. He was named NL Player of the Month in June. Beginning last year, the timing never seemed quite right for Pirates GM Neal Huntington to trade the 2013 NL MVP Award winner. That's probably going to change in the next few weeks.

Teams shopping: Twins, Mariners, Rangers

Metrics suggest McCutchen is a better fit in an outfield corner, where he began the season, but the Rangers could acquire him with an eye toward 2018. (The Mariners probably need a glove-first center fielder, given the dimensions of Safeco Field.) The Twins could add a left-handed complement to Byron Buxton , depending on how well the team plays -- and how much contact he makes -- coming out of the break.

Corner outfielders

Top names:J.D. Martinez, Melky Cabrera , Seth Smith, Jay Bruce , Curtis Granderson , Jose Bautista , Randal Grichuk , Rajai Davis , Matt Joyce, Daniel Nava , Hunter Pence

Martinez hasn't drawn the widespread interest the Tigers (and many observers) expected, at least among NL clubs, due to concerns about his defense in right field. He's still affected by the sprained Lisfranc ligament in his right foot, suffered in Spring Training, but Martinez's 146 OPS+ ranks fourth among MLB outfielders since 2014, behind Michael Trout , Bryce Harper and Giancarlo Stanton .

Teams shopping: Rangers, Royals, D-backs, Dodgers, Rockies, Angels

Finally, the Mets are weeks away from alleviating their outfield surplus by trading Granderson, Bruce or both. (At least, we think so.) Granderson, long one of the most revered people in the Major Leagues, has enhanced his marketability by amassing a .988 OPS following his horrendous April. Smith's left-handed bat, solid season and expiring contract make him a strong trade candidate. Nava, a World Series champion with the Red Sox four years ago, has been quietly productive with the Phillies in a part-time role.

Designated hitters

Top names: Nelson Cruz , Shin-Soo Choo , Mark Trumbo , Victor Martinez

The Mariners aren't "shopping" Cruz, but they aren't going all-in at the Deadline, either, which raises obvious questions about the future of a DH signed only through 2018. After such an active offseason, though, Mariners GM Jerry Dipoto may opt for a quiet Deadline -- unless he can address the team's long-term rotation needs.

Teams shopping: Royals, Rangers

AL clubs rarely trade for a pure DH these days, making a deal in this position group somewhat unlikely. Seth Smith, mentioned in the outfield section above, could have DH duties if he's traded. Brandon Moss (.657 OPS) is under contract through next year, making it unlikely the Royals will replace him by July 31.