49ers’ joint practice vs. Chargers turns into a backup showcase, with Kaelon Black standing out

The San Francisco 49ers’ latest joint practice look carried a familiar preseason theme: when the starters left the field, the competition did not. After the team went to work in the same sessions with the Los Angeles Chargers that included Brock Purdy and the “starters” playing only a single drive, the game-type reps shifted to backups and players fighting for roster spots.

According to Yahoo Sports’ snap-count and grade-style breakdown from Thursday night at SoFi Stadium, the 49ers’ overall level did not drop after the first wave. San Francisco’s second group kept pace in a way that shaped the evening’s narrative, culminating in what the report describes as a 40-burger against the Chargers. In other words, the performance was not limited to early scripted tempo or first-team efficiency.

At the center of that discussion was Kaelon Black, the running back highlighted as “impressive” in the practice-game window. The framing matters because Black’s impact was tied to a broader roster conversation, with the piece specifically asking whether there is “a new RB2 in town,” suggesting the 49ers’ evaluation is tracking who can consistently support the team’s lead back role behind the starter.

The report also indicates that the 49ers’ dominance did not come from one facet. It characterizes the effort as continued across the board after the starters gave way to the backup unit. That matters in roster-building terms because preseason evaluation for depth players is often as much about fit and consistency as it is about isolated highlight plays.

For the Chargers, the session was part of Jim Harbaugh’s ongoing organizational emphasis on evaluation in real-game tempo rather than only walk-through execution. For San Francisco, it reinforced that the team’s coaching staff is willing to let meaningful reps play out, using the first drive as a baseline before shifting the spotlight to the next wave of players who still need to earn specific roles.

There is an obvious caveat to placing too much weight on any one joint practice. Snap counts and grades are influenced by game planning, how long certain personnel groups stay on the field, and the matchup patterns each team chooses. Still, the way the 49ers’ depth group carried the evening provides a clear data point for who is separating from the pack in training camp-type evaluation.

What to watch next is whether the running back competition the report points to translates into more repeatable outcomes in subsequent practices and games. If the 49ers continue to show that they can generate offense with the second unit, the RB2 discussion is likely to stay active, and Kaelon Black’s role in those reps will be a primary storyline.