by Jeremy Plonk
April 5, 2021
Welcome to a continuing handicapping series for our Monday blog space, “Monday Myths.” Each week I’ll use the power of the Betmix database to take common handicapping assumptions and either support or dispel them with data. Betmix data powers the 1/ST BET app and its features like Angler and Birddog give data-minded horseplayers a treasure trove of information in which to query your own curiosities.
Turf-to-dirt surface changes can be a positive move for handicappers to follow.
Saturday’s Grade 1 Santa Anita Derby blitz by Rock Your World turned heads in that colt’s first start on the dirt after 2 turf victories. While you’ll often hear horseplayers tout the “turf-to-dirt” angle, can we validate that as a positive move overall, or in certain situations?
I crunched the numbers in the Betmix database for every dirt Thoroughbred race in North America over the past 5 years, going back to April 5, 2016. The study looked at last-out turf runners making their surface change to dirt. I separated horses by class, from maidens to claiming to allowance to listed stakes to graded stakes. I also looked at turf-to-dirt movers of various expectations in terms of odds.
Maiden claiming horses going turf-to-dirt won 13.7% and had a $1 ROI of $0.75.
Maiden special weight horses going turf-to-dirt won 12.5% and had a $1 ROI of $0.76.
Claiming horses going turf-to-dirt won 12.4% and had a $1 ROI of $0.77.
Allowance horses going turf-to-dirt won 12.2% and had a $1 ROI of $0.76.
Non-grade stakes horses going turf-to-dirt won 10.8% and had a $1 ROI of $.69.
Graded stakes horses going turf-to-dirt won 10.4% and had a $1 ROI of $.86.
Favorites going turf-to-dirt won 37.1% and had a $1 ROI of $0.83 (dirt-dirt 38.5%, $0.84).
Horses 5-1 or less going turf-to-dirt won 24.8% and had a $1 ROI of $0.79 (dirt-dirt 26.5%, $0.82).
Horses 6-1 to 10-1 going turf-to-dirt won 8.9% and had a $1 ROI of $0.77 (dirt-dirt 9.3%, $80).
Horses 11-1 to 15-1 going turf to dirt won 5.1% and had a $1 ROI of $0.70 (dirt-dirt 5.7%, $.78).
Horses 15-1 or more going turf to dirt won 2.5% and had a $1 ROI of $0.63 (dirt-dirt 2.2%, $0.59).
In terms of race classes, turf-to-dirt movers won at a higher percentage in the cheaper class of races and dropped at every single rise up the class ladder. The ROI betting turf-to-dirt runners was consistent up until the stakes class, then took wild swings.
In terms of public expectation, turf-to-dirt movers had a lower win percentage and lower ROI at every studied betting level, including the actual race favorites, until you got to the longest of longshots. The drop in productivity was consistent.
Overall Findings Verdict:
Consistently the statistics show that betting horses moving from turf-to-dirt is a long-range uphill battle. If you’re going to do it, the mostly likely winners come at the cheaper levels, but the most profitable approach is in the graded stakes in terms of ROI, such as we saw with Rock Your World in the Santa Anita Derby. All things being equal, in terms of betting odds and probabilities, you’re better off betting dirt-to-dirt runners than turf-to-dirt at any odds level up until a slight edge for the surface changers when looking at the longest of longshots.
The myth of successfully betting horses turf-to-dirt is anecdotal and may work in some cases, but there’s more than enough statistical evidence to show that it’s not a consistent winner. Use turf-to-dirt statistics with particular trainers to uncover ones who have made the most with success in the past, but don’t project it to be a winning move without individual numbers to back it up.
You can go into Betmix and run your own queries for a deeper dive into this theory and any that you can create. For instance, take a look at the tracks you play most often to see if they fall in line with this study’s conclusions, and certainly a turf-to-dirt trainer angle with a particular barn may be far more successful than others. For instance, the database shows Finger Lakes and Thistledown among the best places to bet a turf-to-dirt mover (neither track has grass and gets shippers on the drop in class).