Weekly Fantasy Start-Sit Advice

Fantasy Math is a premium service for weekly start-sit advice.
: put in your matchup (you and your opponents lineup), the players you're deciding between, get back the probability you win.
Other sites (Yahoo, ESPN, Fleaflicker) show win probabilities, but Fantasy Math is the only site modeling player point projections as explicit distributions. More on the advantages that gives below.

Projections as Probability Distributions

"The fundamental problem in fantasy football isn't maximizing your expected total points, it's maximizing the probability you score more points than whoever you're playing this week."
Fantasy Math is able to tell you who maximizes your probability of winning because it starts with full probability distributions for every player.
It looks something like this:
PPR RB, week 14 last year. CMC is good
PPR RB, week 14 last year. CMC is good.
Remember, there's a subtle difference between setting your lineup to score the most points possible, vs trying to score more than your opponent.
Working with full point distributions like Fantasy Math does (vs point estimates or rankings) get at this difference by letting you take into account:

, or how boom-or-bust a player is

Say you're down by 45 points going into a Monday night CLE-HOU game with one player to go. Would you rather start Will Fuller or Jarvis Landry? What if you were down 10 points?
Normal rankings and projections can't factor this in at all. But since Fantasy Math models the entire distribution, it can tell you that Will Fuller has a higher change of scoring 45 or more than Jarvis Landry.

, the tendency of players' scores to move together.

Once we have a projected distribution for each player, Fantasy Math takes thousands of correlated draws from each one. This lets you factor real-life correlations into your decision.
For example:
Imagine you have a close call — say
Tyler Lockett
Stefon Diggs
— and your opponent is starting
Russel Wilson
. The fact Wilson and Lockett's points are positively correlated (about 0.44) might affect your optimal decision.
Precisely HOW it affects your decision depends on the rest of your matchup:
if you're heavily favored, the correlation might mean you should start Lockett as a hedge against Wilson blowing up
if you're the underdog, maybe you need Wilson to underperform AND Diggs do really well to have any chance at all, which means Diggs maximizes your probability of winning
Fantasy Math takes all this into account. And not only the correlation between same team QB-WR, but every pair of simultaneous correlations (e.g. Lockett and Wilson together are correlated, but they're also both correlated with Chris Carson, DK Metcalf and the QB of the team Seattle is playing against) — between same and opposing QB, RB, WR, TE, K, DST.

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The Second Best "Who Do I Start Advice" You Can Get

It's easier to understand why Fantasy Math is the best start-sit advice you can get by considering the
second best
advice you can get:
I have an economics background, and I've always been a big believer in efficient markets and the wisdom of crowds. I draft by
selecting the biggest bargain according to ADP
, and my investments are in index funds.
Expert Consensus Rankings — where hundreds of experts submit their fantasy rankings each week — are clearly the fantasy football equivalent of that. And so if the goal is maximizing point totals, efficient markets would suggest — just as index funds beat stock picking — that's the best most of us (even experts) can expect to do.
At the risk of giving away some secret formula
, Fantasy Math is basically ECR with correlations and player variance added on top (one cool thing: the more experts disagree about a particular player, the wider his distribution).
Because the goal in fantasy is beat your opponent rather than maximizing your total points, this gives Fantasy Math a slight edge over ECR, which is probably way ahead of anything else itself.

The Fantasy Math Edge

While real, the Fantasy Math edge is small.
The main reason for this is that optimal start-sit decisions are mainly driven by the scale parameter (i.e. start the guy whose distribution is furthest to the right), which traditional rankings and point estimates get at fine. Correlations and shape (aka variance aka boom or bust) are secondary.
I'm not even sure — compared to just using
Boris Chen
(which is also based off of ECR) — the impact on expected wins/share of league winnings is worth the price, just as a pure monetary, expected value calculation. Probably depends on your entry fee.
But fantasy is a game of small edges, and good players won't rest until they've uncovered every possible one.
If this sounds relatable — if you spend more time on fantasy than you'd care to admit and won't be able to rest until you've wrung every last drop of win probability out of your lineup each week — then Fantasy Math might be for you.

What People Are Saying

I freaking love this
. It's a beautiful idea and so far looks like a great execution of it."
Dylan Lerch, aka u/quickonthedrawl
"This is an
outstanding way to visualize the choices we make every week
and why there are not necessarily one size fits all "right" answers,
different curves make more sense for different lineups/matchups
Sigmund Bloom, Co-owner of footballguys.com
No other tool I've ever come across has done this
... I've considered [incorporating correlations] as a competitive advantage of mine for a number of years, but wasn't able to properly and consistently quantify those values in a truly objective measure..."
Seth K
"It’s an
incredible site
. I have no idea how you worked the math into this."
Ben R
"...this is the first site I have seen that looks like it might
match the standards I'd have for a subscription service.
David S

New models coming soon! Subscribe for updates

Fantasy Math is undergoing changes this offseason, including a rebuilt WDIS model that'll be more accurate + flexible than ever. Enter your email to stay tuned for updates.
Get Notified!