• Nerd Nook

Why +EV Bets Don’t Always Win

Sports betting has never been more popular, and with it comes more talk about finding an edge. One of the most common terms you’ll hear is +EV betting, short for positive expected value. The idea is simple: if you’re consistently betting at odds better than the true probability, you should make money in the long run.

That “long run” part is where bettors often get tripped up. You can place a bet that has positive EV and still lose that night. Understanding why is key to making smart, sustainable betting decisions.

What Is Positive Expected Value?

Expected value (EV) is a math concept that tells you the average amount you stand to win or lose per bet. It takes into account both the probability of winning and the payout you’ll receive. The formula looks like this:

EV = (Win Probability × Payout) – (Loss Probability × Stake).

If the result is above zero, that’s a +EV bet. If it’s below zero, you’re playing a losing game over time.

Example: Imagine a coin toss with even odds. A fair line is +100 on both sides. If a sportsbook offers +110 on heads, you’ve got a +EV opportunity. The payout is higher than the true odds, which gives you a small edge over thousands of flips.

In sports betting, this usually happens when you think a sportsbook’s line doesn’t reflect the true probability. Maybe a team is listed at +150 but you’ve calculated their real chances at closer to +120. If you’re right, you’re betting into a mispriced line. That’s the essence of expected value betting: consistently finding numbers that tilt the math in your favor.

Variance and Short-Term Results

So if a bet has positive EV, why doesn’t it always win? The answer is variance. Variance is just the natural swings in results that come with randomness.

Let’s use the coin flip example again. Over 1,000 flips, the results will come close to 50/50. But in a sample of 10 flips, you could easily get seven heads and three tails. That doesn’t mean the odds were wrong. It’s just variance at work.

Sports betting works the same way. You can be on the right side of the math and still lose five straight wagers. That doesn’t mean your edge disappeared. It means you need enough volume for the math to even out.

This is where many bettors get frustrated. They see a good bet lose and assume the concept of EV is flawed. In reality, losing streaks are baked into the process.

Sample Size & The Law of Large Numbers

To make +EV betting work, you need a big enough sample size. The law of large numbers says that as you increase the number of trials, the actual results will get closer to the expected outcome.

Take blackjack as an example. Basic strategy against a standard house edge will still lose in the short run. Over hundreds of thousands of hands, though, the results will line up closely with the house’s built-in percentage edge.

For sports betting, this means one weekend of NFL bets doesn’t prove anything. Even a single season may not be enough to fully show your edge. The real value comes from placing thousands of bets where you consistently get the better of the number.

Volume matters. The more opportunities you take at positive EV spots, the more your results will resemble the math. Bettors who give up after a few unlucky weeks never get to see their edge pay off.

Short-Term vs. Long-Term Results of +EV Betting

Timeframe	What You’ll See	Why It Happens	Takeaway for Bettors
1–10 bets	Wild swings in results. A +EV bet might lose multiple times in a row.	Variance dominates small samples.	Don’t panic. Losing streaks don’t prove the math wrong.
50–200 bets	Results start to move closer to the true edge, but streaks still happen.	Variance is still in play, but the sample is big enough to show patterns.	Stick to your staking plan. You’re starting to see progress.
500+ bets	Results strongly reflect expected value. Edges show up clearly.	The law of large numbers smooths out randomness.	Volume and patience are what make +EV profitable.

Bankroll Management for +EV Bettors

Finding +EV bets is only half the equation. Managing your bankroll is what keeps you in the game long enough for the math to work.

A common rule is to risk only 1–2% of your bankroll per bet. This protects you from going broke when variance hits. If you have a $5,000 roll, that means your bet size should usually fall between $50 and $100.

Another key is avoiding “all-in” thinking. Even the sharpest bet in the world can lose. Putting too much of your bankroll on a single game can wipe you out before your edge shows up.

Some bettors also use the Kelly Criterion, a formula that sizes bets based on edge and bankroll. It can help maximize long-term growth, but it’s aggressive if your edge estimates are off. Most recreational bettors are better off sticking with fixed percentages.

Good bankroll management is boring, but it’s what lets you weather the inevitable losing streaks and still keep firing.

Common Mistakes Bettors Make with +EV Strategies

Even with a solid understanding of EV, it’s easy to fall into traps. Here are some of the most common mistakes:

1. Expecting instant results. Many bettors think a +EV bet should win that night. When it doesn’t, they lose faith in the process.

2. Betting on too small a sample. Playing only a handful of games each week makes variance feel bigger than it is.

3. Overestimating your edge. If your true read of probabilities is off, what looks like +EV may actually be negative EV. That’s why tracking closing line value (CLV) is so important.

4. Chasing losses. Losing streaks make some bettors raise their bet size to “get even.” This kills bankrolls faster than anything.

5. Ignoring the market. A line that looks good at +150 may be bad at +120. Timing matters. You need to shop lines and be patient.

Avoiding these mistakes won’t guarantee profits, but it makes sure variance is the only thing standing between you and long-term success.

Real-World Examples of +EV in Action

Sports Betting

Let’s say you’re betting MLB underdogs. You calculate that a team has a 40% chance of winning, which should make their fair odds +150. The book lists them at +180. That’s a +EV wager.

You’ll lose more of these bets than you win. But if your read is right, the wins pay out enough to cover the losses and leave you ahead.

Casino Games

Casinos flip the math the other way. Games like slots or roulette are built with negative EV. A roulette wheel with a double zero has a house edge of about 5.26%. That means if you play long enough, the casino will always come out ahead.

Poker

Poker is different because you’re playing other people, not the house. Every decision has an expected value, and good players constantly seek +EV spots. Folding a marginal hand in a bad position can be +EV if it saves chips for a better spot later.

DFS and Prop Betting

Even daily fantasy sports and prop markets involve EV thinking. If you’re consistently finding player props with mispriced odds, you’re making +EV bets. Like sports betting, though, variance means you won’t cash every ticket.

Why Patience and Discipline Matter

At the heart of +EV betting is patience. A single losing night doesn’t matter. A bad month doesn’t even matter if you’re consistently finding the right numbers.

Discipline is what separates bettors who profit from those who don’t. Sticking to small bet sizes, focusing on process, and trusting the math is what makes the edge real.

Most gamblers chase short-term highs. +EV bettors play the long game, knowing the swings will even out if they don’t quit early.

Summary

Positive EV betting is the foundation of sharp sports betting strategy. It means getting money down when the odds are in your favor. But variance, small sample sizes, and poor bankroll management can make even good bets lose in the short run.

The edge shows up with patience, volume, and discipline. Betting into +EV lines doesn’t guarantee tonight’s ticket cashes, but it’s the closest thing to a winning formula in the gambling world. For bettors who want to go deeper into the numbers behind the odds, check out our Nerd Nook section, where we break down the math that powers profitable betting.