Why the initial value often decrease in value betting

So why is it that average CLV and yield is always lower than your average value at bet placement in the long run?

The major reason is that the sharp bookmaker margin typically shrinks over time. As we get closer to match start, the sharp bookmakers get more confident in their odds, thus lowering the margin. As margins shrink, sharp odds will increase slightly, bringing down the value of the bet.

As explained by Joseph Buchdahl: "where net market movement is zero between opening and closure, a closing price will still be a little longer [higher, less likely] than it's opening one".

But let's dig a bit deeper.

Another major reason is mean reversion.
Since you only bet when the soft line disagrees with the sharps in your favor. Running a regression analysis of millions of value bets shows the market later adopts ~10% of that disagreement (β ≈ 0.10). That means most of your initially measured edge mean-reverts toward the consensus before close.

A small built-in headwind
Even when the initial gap is tiny, the closing move has a slight bias against your side. That could be order-flow effects (arbitrage hedging, bookmaker shading). It's small, but it tilts the odds so that small edges shrink more often than they grow.

Value percentage is a ratio, so small adverse moves look big
Even a modest drift in fair odds can chop a large percentage off the value. See this example:

• At placement: Pinnacle fair = 2.00, soft odds = 2.20 → value = +10%.
• By close: Pinnacle fair nudges to 2.08 (only +4% against you).
• CLV = 2.20 / 2.08 − 1 = +5.8% → that's a 42% drop from the original 10%.

Statistics after analyzing 5 million value bets

• 60% of all sharp odds will increase between bet placement and match start (closing odds).
• Value shrinks by 40% on average from bet placement.
• However, if you bet just few hours before match start, it shrinks only around 20% on average.
• 84% of all our value bets still beat the closing line. This is the most important metric in sports betting.
• 69% of all our value bets beat the closing line and still has a positive value (adjusting for margin).

So, while it's frustrating to see the value decreasing, it's a completely expected movement in the betting market. And an average yield of 2.6% per bet will still give you a pretty amazing profit over time. Try to grab as high initial value as possible, it will directly increase your ROI and profit.

You should always bet on the highest value while still turning over your bankroll as often as possible. But since your yield will end up around 40% lower than the average, try to set your minimum value filter accordingly. For example, if you want a 2.6% average yield, your average value at bet placement should be 4.4%.