Short version: The Sunday Chronicle treats each platform as a separate sourceon a single league archive. Past seasons from Yahoo + current seasons from Sleeper can both live under one almanac. After import, you merge cross-platform manager identities so each real person's stats roll up into a single career line.
Why league history dies when you migrate
Fantasy platforms don't talk to each other. When a league moves from Yahoo to ESPN, the new platform starts at year zero — no historical champions, no past drafts, no head-to-heads, nothing carried over. The old platform's data is technically still there, but increasingly hard to access: Yahoo deletes leagues after inactivity, ESPN buries pre-2018 seasons in a legacy archive, NFL.com periodically takes leagues offline entirely.
Most commissioners give up and start tracking the league's history in a Google Sheet. A year later, no one updates the sheet. Two years later, no one remembers who won 2019. The league's story dies.
The "multiple sources" model
On The Sunday Chronicle, a single league can have multiple platform sources attached. Each source contributes the years it covers:
- Yahoo source (2015–2018): imports old champions, drafts, matchups
- ESPN source (2019–2022): imports the middle era
- Sleeper source (2023–present): imports current + auto-syncs weekly
The public almanac at thesundaychronicle.app/leagues/your-league/ shows all 10 seasons as one continuous history. Career standings, head-to-head records, and rivalries are computed across all three eras.
Step-by-step migration
- Create the league archive. Use your most recent platform (typically Sleeper or ESPN) as the primary source. Paste that league ID at signup.
- Sync the primary source. Pulls every season on that platform.
- Add additional sources. Open your league's admin page → Sources → Add. Paste your old league ID from a different platform. Sync that source.
- Merge identities. Open the Members page. Each real person now appears once per platform they played on. Click two rows, click Merge — pick the canonical name. Repeat for each multi-platform commissioner.
- Publish. Toggle the public almanac on. Share the URL with your league.
What gets unified automatically
Once identities are merged, the following roll up across platforms:
- Career wins, losses, and points-for / against
- Championship roll (every title across every platform era)
- Head-to-head records (e.g., your career record vs Joe spans all platforms)
- Top single-week scores, biggest blowouts, longest streaks
- Commissioner-curated rivalries (you can pick a feud that spans multiple eras)
What doesn't carry over
Some platforms don't expose data via API — chat logs, trade discussions, sideline notes, etc. Those are lost when a platform is abandoned. The Sunday Chronicle archives the game record: standings, matchups, drafts, champions, manager performance. The social context lives in your group chat.
FAQ
What if I never had an account on the old platform? The previous commissioner's league ID is enough (for public leagues). Ask them to share it.
How much does multi-source cost? Multiple sources on one league count as one league — Rookie tier ($5/mo) covers it.
Can I add a source years later? Yes — sources can be added anytime. The almanac re-renders with the new history merged in.