Beat Your League

How accurate are Sleeper's own projections?

Nobody had published an answer, so we measured one — and we'll lead with the part that stings: on the decisions both sides could call, Sleeper's free projections beat our own numbers, 68.8% to 64.4%. Here's the whole test, including why we still couldn't just use theirs.

How we tested it

We took a frozen set of real start-sit decisions from a full 2018 league season — the set our earlier league study graded, decided before this test existed, and a different measurement from the grading record the product publishes today — and asked Sleeper's projection feed (which is Rotowire-sourced and free) to make the same calls. Same head-to-heads, same real box scores, same decision rule. No cherry-picking is possible because the question set was locked first.

The head-to-head

SeasonDecisions both could callOur hit rate Sleeper's hit rateThey were right, we were wrong We were right, they were wrong
201836864.4%68.8% 4731

Read the gap with its uncertainty: 47 to 31 on disagreements gives a two-sided p-value of 0.089 — suggestive, not conclusive, on one season of one league. We don't quote the 68.8-vs-64.4 gap without that number, and neither should you. Also honest: the archive has no usable records for 2017, and whether archived projections were ever revised after the fact is unknowable from outside — we graded what the archive holds.

They also missed less

SeasonPlayer-weeksOur average miss Sleeper's average miss
201814946.61 points6.39 points

So why not just use Sleeper's numbers?

Because of what the feed can't see. It carries roughly 400–520 players in any given week — every era we checked — and real bench decisions constantly involve players outside that list. On our frozen decision set it simply had no opinion on 626 of 994 head-to-heads: nearly two out of three real decisions, unanswerable from the feed alone.

Its one unambiguous win is Week 1, where it projects most starters while any history-based approach is still waiting for a game to be played. Its structural loss is depth, which is exactly where start-sit decisions live.

What we did about it

Nothing quietly. Our reports keep publishing our own numbers, with the calls graded in public — and this page stays up, including the table where the free feed beats us, because one league-season of evidence is enough to decide what to test next, not enough to bury. If we ever blend the feed in, the ranges and confidence rules get re-tested first; until then, what you see in a report is what has been measured.

The same honesty applies to the product: every call we publish is graded against the real box score on a public page — wins and misses both.
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