Over the last six weeks, we’ve been releasing select QB yardage prop bets (full ledger below). Thus far, these bets have a record of 18-13 for a respectable 58.1% winning percentage. Let’s ask ourselves however, if this record is reflective of our underlying performance by analyzing our margin of victory (MOV).
MOV Analysis is pretty straightforward: rather than grading your performance based on wins and losses (binary outcomes) we can assess the magnitude of the win to get a more granular assessment of performance.
While analyzing MOV is inherently assessing performance against the mean (and as bettors we are more concerned about the median of a distribution of potential outcomes) it is still a useful exercise. If your wins are consistent by a sizable margin while your losses are often very close, your model might be more useful than your record indicates. Conversely, if you're only winning close bets and your losses are by a sizable margin, your record might not be sustainable.
Across the 31 bets above, we’ve had an average MOV of 30.8 yards. Yes, we’ve had a couple games where QBs were removed from the game early due to injury (which is source of value of any under on a prop bet), but that doesn’t make up for our aggregate MOV of nearly 954.5 yards (Average MOV: 30.8 x 31 games = 954.5 aggregate MOV).
We’re very happy with these MOV figures. What’s even more reassuring (since we bet almost exclusively unders) is that QB passing yards generally have a positive skew resulting in a mean that exceeds the median by 4-5 yards. To translate: over the long run, if you’re betting unders and win 50% of the time, we’d expect your MOV to hover around -4 to -5 yards.
So how should we feel about our performance thus far and our outlook going forward? Very strong. Based on our expected distribution of passing yards for QBs, we’d expect an average MOV of 30 to translate to a winning percentage of approximately 65%. This winning percentage may seem far-fetched for spreads and totals, but not out of the realm of possibilities for less liquid markets like prop bets.
Will our winning percentage on these bets climb from 58% to 65%? Who knows. This is still an incredibly small sample size and our underlying performance could be on the right side of variance. However, our average MOV gives us confidence that we’re on the right track.