Here are the position players that have recently taken to the open market, along with their now-former teams (via the International League and PCL transactions pages):

• Jim Adduci, OF, Cubs
• Aaron Altherr, OF, Mets
• Rob Brantly, C, Phillies
• Wilkin Castillo, C, Marlins
• Isaac Galloway, OF, Marlins
• Dustin Garneau, C, Athletics
• Juan Graterol, C, Reds
• Gorkys Hernandez, OF, Red Sox
• Oscar Hernandez, C, Red Sox
• Rafael Lopez, C, Braves
• Deven Marrero, INF, Marlins
• Peter O’Brien, OF, Marlins
• Jace Peterson, IF/OF, Orioles
• Yadiel Rivera, 3B, Marlins
• JB Shuck, OF, Pirates
• Jesus Sucre, C, Orioles
• Blake Swihart, C/OF, Diamondbacks
• Beau Taylor, C, Athletics
• Charlie Tilson, OF, White Sox
• Bobby Wilson, C, Tigers

• Marlins catcher Wilkin Castillo is headed back to the Triple-A roster after being outrighted, per the PCL transactions page. The 35-year-old had returned to the majors this season for the first time since 2009, though he only appeared in two contests. An exceptionally versatile player, Castillo has spent most of his professional career behind the dish but has also lined up at every other position on the field. (Only barely. Though he has five pitching appearances, Castillo has logged just one inning in center field.)
• The Mets outrighted southpaw Donnie Hart to their top affiliate after he cleared waivers, the International League transactions page reflects. Hart, who turns 29 tomorrow, has spent time this year with the Mets and Brewers. He previously appeared in parts of three seasons with the Orioles. While Hart carries a 3.13 ERA in 89 career MLB innings, that relies heavily upon his unsustainable debut showing (one earned run in 18 1/3 innings in 2016). Though he hasn’t been much of a strikeout pitcher in the big leagues, the soft-tossing lefty does have a career 54.1% groundball rate.

Sierra, 23, will rejoin the club for the first time since the 2018 season. Acquired with Sandy Alcantara in the trade that sent Marcell Ozuna to St. Louis, it was hoped that he could serve as a long-term piece in the Miami outfield mix. That didn’t look to be the case by any stretch of the imagination in 2018 when Sierra batted just .190/.222/.211 in 156 big league plate appearances with the Marlins. His 2019 season in the minors has been better but not particularly impressive; in 549 trips to the plate between Double-A and Triple-A, Sierra has batted .275/.316/.387 with seven homers, 19 doubles, nine triples and 33 stolen bases (in 44 attempts).

This will be a big month for Sierra, who’ll be out of minor league options in 2020. That’s not to say he’s at jeopardy of losing his 40-man spot if he doesn’t show well in September, but a strong final impression in 2019 would surely improve his positioning for the 2020 campaign. Conversely, if he flounders in a similar fashion to his 2018 struggles, he’ll make it difficult for the organization to bank on any contributions from him next year.

Neither Heineman nor Moran seems like a long-term piece for the Marlins, but each will get his first look at the MLB level this month. Heineman, 28, was acquired from the D-backs in exchange for cash back in June. He’s batted a combined .336/.400/.590 in the Pacific Coast League’s supercharged offensive environment but has never hit much in four prior seasons at that level (most coming with the Astros, who drafted him in the eighth round back in 2012).

Moran will turn 31 later this month and has grinded through 10 minor league seasons leading up to today’s breakthrough to the Major Leagues. It’s undoubtedly an emotional day for the former Mariners farmhand, who has pitched to a 3.15 ERA with 11.6 K/9 against 3.9 BB/9 in 60 innings of relief in New Orleans this season. Moran has spent parts of five seasons in Triple-A, compiling a 3.67 ERA with 11.5 K/9 and 3.2 BB/9 in 176 2/3 innings.

Anderson was already known to be done for the season after incurring a fractured hand last month. Miami’s best all-around player, the 26-year-old Anderson batted .261/.342/.468 with a career-high 20 home runs and 33 doubles in 520 plate appearances this year. He’s controlled all the way through the 2023 season and looks like a building block in South Florida.

Castillo, meanwhile, returned to the Majors in 2019 for the first time in a decade. He appeared in just two games but nonetheless was able to relish the bright lights of the Major Leagues after a long journey through the minors. Castillo has just 24 big league games to his credit, but the 35-year-old has played in 581 career Triple-A games, hitting .245/.283/.358 along the way.

Alfaro, who suffered his injury in the Marlins’ win over the Cardinals on Thursday, has hit .261/.312/.419 (96 wRC+) with nine home runs in 218 plate appearances during his first year with the Fish. That’s fine production for a catcher, which is something the Marlins were hoping for when they acquired Alfaro in a trade with the Phillies for star backstop J.T. Realmuto last winter.

Despite his solid output, Alfaro hasn’t overcome the plate discipline woes that plagued him with his previous organization. So far this season, the 26-year-old has posted a 33 percent strikeout rate against a paltry 3.7 walk percentage. At the same time, though, Alfaro has earned plus marks behind the plate, where he has used his big arm to throw out 35 percent of would-be base stealers.

Castillo, 35, inked a minor league deal with the Marlins during the offseason. He’s now in line to back up Bryan Holaday, which will make for Castillo’s first major league action since 2008-09 with the Reds. Castillo totaled a mere 37 trips to the plate in the majors during that span. He’s a lifetime .245/.283/.352 hitter in 2,014 attempts at the Triple-A level.