Answered with numbers you can check — including ours.
The Kelly criterion sets your stake as a fraction of your bankroll based on how big your edge is and what price you are getting. Bigger edge, bigger stake; thin edge, small stake; no edge, no bet. The formula for a simple win/lose bet is (bp - q) / b, where b is the decimal odds minus one, p is your estimated win probability and q is 1 - p.
Its appeal is that it maximises long-run growth of the bankroll. Its danger is that it does so only if your probability estimate is correct. Overestimate your edge - which almost everyone does - and Kelly sizes the bet far too large, and drawdowns become brutal.
That is why serious users run fractional Kelly, typically a quarter or a half, or cap the maximum stake outright. The growth penalty is small and the reduction in variance is large.
Flat staking - the same unit on every bet - is the honest comparison baseline, and it is what published ROI figures should use. Variable staking can make a mediocre record look excellent simply by sizing the winners bigger in hindsight. MalluSports sizes with a capped Kelly but publishes ROI at flat one-unit stakes for exactly that reason.
MalluSports is a free prediction and analysis service only. It accepts no bets, holds no funds, operates no gambling platform and holds no gambling licence. Betting carries real financial risk. 18+ · begambleaware.org