San Francisco’s defense leapt off the tape in preseason, blending aggressive pressure with versatile coverage. Nick Bosa’s lingering soreness looms as a staffing concern, while the run of camp bodies and depth pieces on the 49ers’ back end reshapes Week 1 projections. Bo Nix’s Broncos slate provided a contrasting test, with Daniel-esque pressure forcing quick checks and post-snap reads that underscored Salah’s scheme as a force multiplier rather than a one-man show. Chase Lucas flashed as a key contributor in man coverage, and Kalia Davis and Tatum Bethune emerged as real depth pieces who can impact the defensive ceiling sooner than expected. The film breakdown highlighted Seattle-3 roots, palms/quarters reads, and fire-zone blitzes that keep offenses guessing and allow Bosa, Huff, and Williams to generate pressure with four rushers. The unit’s cohesion—backed by disciplined tackling and crisp zone-coverage transitions—suggests San Francisco can escalate from a strength of its roster to a true schemed-strength defense, even if Week 1 health luck remains a concern. Fantasy takeaway: monitor Bosa’s practice status, value Lucas and Bethune as interim defensive darts, and anticipate more intricate blitz packages that boost multiple San Francisco players beyond the stars.