Sept roster expansion accelerates a wave of rookies and returnees across MLB fantasy rosters. Mets promote Jonah Tong and Nolan McLean to help a six-man rotation down the stretch; Boston tab Payton Tolle to stabilize a rookie-heavy brood. Cincinnati’s Sal Stewart and Kansas City’s Carter Jensen arrive with multi-position upside, while Miami’s Connor Norby and Arizona’s Jordan Lawlar return from injuries and search for steady at-bats. The Reds also lean on Sal Stewart for spark while Perdomo’s extension with Arizona locks in infield predictability.

Risers collide with risk as first-timers settle in: Tong’s debut win over Miami signals potential multi-start value; Tolle impressed enough to stay in the rotation through September; Norby and Lawlar offer speculative upside in shallower formats; Ke’Bryan Hayes’ move (via trade context) and Perdomo’s extension shape the infield depth for late-season fantasy planning.

Chicago White Sox exploded for a season-best 13 runs in Atlanta, snapping a four-game skid with a shootout victory over the Braves. The offense finally woke up behind a trio of long balls and a six-run fourth inning that turned a lopsided game into a showcase for projection hits and depth pieces. Colson Montgomery left with left-side soreness, but young bats carried the day as Lenyn Sosa anchored the middle of the lineup with a 439-foot two-run shot in the sixth and a run-scoring single earlier in the contest. Brooks Baldwin set the tone with a 404-foot solo blast off Spencer Strider in the third, and Kyle Teel and Chase Meidroth added timely hits to keep the pressure on. Luis Robert Jr. joined the party with a two-run homer, ending a two-week drought and signaling a much-needed spark from the heart of the lineup. The Sox piled on after chasing Strider, taking advantage of a short bullpen night for Atlanta and padding the cushion late with Teel’s solo shot and Meidroth’s RBI hits to seal a 13-9 win. On the mound, Yoendrys Gómez navigated five innings with three earned runs as Atlanta briefly climbed back into it, while the White Sox announced a rotation shakeup, with Martin Pérez returning to start in Atlanta and Owen White being recalled to the bullpen. Outside the game, Colorado’s sinking season continued as the Rockies flirted with history, while Dodgers’ scraps of the past hinted at the broader sport’s volatility and the White Sox’s willingness to ride their young core to offensive upside.

In Week 19 of 2025, fantasy baseball managers should focus on promising prospects who are rising through the ranks. Sal Stewart, a versatile infielder for the Cincinnati Reds, has shown exceptional performance at Triple-A Louisville, boasting a .300 batting average with four home runs in just ten games. However, his path to the majors may be complicated by the Reds' recent acquisition of Ke'Bryan Hayes, potentially limiting Stewart's playing time this season.

Dylan Beavers of the Baltimore Orioles may provide more immediate impact, especially after the team's outfield shakeup. Beavers' recent .302 average at Triple-A Norfolk and 21 stolen bases make him a viable option to stash for deeper leagues. Lastly, Jonah Tong, a standout pitcher for the New York Mets, has maintained an astounding 1.72 ERA at Double-A, positioning himself as a must-stash for keeper leagues despite the Mets' reluctance to promote him. Each of these players reflects the potential to alter fantasy rosters as the season progresses.

Identifying trends in MLB lineups is crucial for fantasy managers looking to capitalize on undervalued or overvalued players. For instance, the Atlanta Braves' Marcell Ozuna has seen his playing time diminish with just one start in the last five games, making him a potential trade candidate. Meanwhile, Nacho Alvarez is taking advantage of Austin Riley's injury, showing defensive prowess but struggling offensively.

The Miami Marlins face challenges with Connor Norby's injury, leading to a strict platoon at third base. Agustin Ramirez, despite questions about his long-term viability as a catcher, is starting regularly, offering daily lineup consistency. The New York Mets' Francisco Alvarez returns to the lineup with a strong hard-hit rate, while Jeff McNeil adapts to various positions, showing versatility.

Continuing the analysis, the Philadelphia Phillies' Otto Kemp steps up in Alec Bohm's absence, impressing with his contact quality. Josh Bell of the Nationals is on a hot streak but struggles against lefties, while Riley Adams fills in behind the plate, showcasing power but high strikeout tendencies. The Chicago Cubs' Ian Happ's batting order slotting raises questions about his consistency, as does Matt Shaw's reduced playing time at third base.

Connor Norby of the Miami Marlins faces a significant setback as he undergoes surgery to repair a broken hamate bone in his left wrist. The operation, performed by Dr. Don Sheridan, is expected to sideline him for six to eight weeks. Initially, Norby had been dealing with wrist inflammation but was showing signs of improvement prior to the injury. In his rookie season, he recorded a .241 batting average with six home runs and 26 RBIs over 72 games.

The Marlins will need to adjust their lineup during his absence, with Graham Pauley and Javier Sanoja stepping in at third base. Pauley has already played 23 games at the position this season, while Sanoja has made nine appearances. Manager Clayton McCullough expressed hope that Norby would have made further strides if not for the injury, but now the team must regroup as they begin a critical six-game homestand.