Two numbers sit side by side on an author’s page: ROI and the change in bankroll. They are often read as the same thing, wrongly: they answer different questions and can diverge in opposite directions.
ROI: return per unit staked
An author placed 100 bets of 1,000 each and got 104,000 back. ROI = +4%. The figure does not depend on the order in which wins came, nor on the size of the bankroll. It describes the picks themselves: what an average unit staked brings back.
ROI is convenient for comparing authors, but it has two weak spots. It says nothing about risk: +4% on a hundred bets at 1.30 and +4% on a hundred bets at 4.00 are very different variance. And it means little on a short sample: an ROI of ±30% over 20 bets is business as usual.
Bankroll growth: what happened to the money
The bankroll is the notional sum an author starts a feed with. Each bet deducts its stake from it; each settlement returns the payout. The bankroll curve on the author page shows how that sum moved over time, next to the maximum drawdown: the deepest fall from a previous peak.
Bankroll growth depends on what ROI leaves out: stake size and the order of results. Two authors with the same ROI end up with different bankrolls if one stakes 2% and the other 10%: the second grows faster on a winning streak and loses faster on a losing one. With large enough stakes a positive ROI coexists with a bankroll that ultimately heads to zero, which is exactly why drawdown is shown as a separate number.
Reading them together
- Positive ROI, bankroll growing steadily, small drawdown: the author makes money and keeps stake sizes under control.
- Positive ROI, bankroll grew then dropped sharply: either a losing streak on large stakes, or the author’s stake sizes do not match their accuracy. Look at the average stake and the drawdown.
- ROI around zero, bankroll up: usually one or two lucky large bets. Check the CLV: if it is not positive, regression to the mean is ahead.
What the service does so the numbers cannot be polished
ROI and bankroll are computed by the platform from locked bets, not entered by the author. A bet cannot be deleted or edited after publication, the result is derived automatically from the match outcome, and the stake is fixed as a share of the bankroll at the moment of publication. More on the mechanism in the article on locking picks; the settlement and admission rules are in the methodology.
About the sample
Next to ROI on the author page there is a confidence interval. It is wide for new authors and narrows with the number of settled picks. As long as the interval covers zero, the ROI figure means “not clear yet” rather than “plus” or “minus”. That is exactly why the rating has a minimum number of picks for each period.