Question #2: How can we measure a player’s finishing ability?
Checkout percentage, or doubles percentage, has always struck me as severely limited. It’s fine for what it measures, but it’s focus is exclusively on the final double. That’s great if you’re interested in the specific skill of hitting doubles. But when I think about the process of finishing a leg it seems overly narrow. The final double is only one part of the checkout process.
Consider the scenario where a player has 40 remaining. They hit S20, S10, then checkout on D5. They only hit on 1 of 3 doubles so their percentage is 33%. If the next player hits the initial D20, their doubles percentage is 100%. But in my mind those two results are the same. In both cases the player had one opportunity for a checkout. And in both cases the player successfully converted that opportunity. A metric that measures finishing ability should assign both players equal credit for a successful checkout conversion.
I propose using a statistic that measures the rate at which a player successfully converts their checkout opportunities into checkouts. What percentage of their checkout opportunities does a player actually checkout? A checkout opportunity is simply defined as a visit to the oche “on a finish” – with a score remaining that can be reduced to zero in three or fewer throws. A successful checkout is any visit where the player reduces their remaining score to zero and wins the leg. The Checkout Conversion Rate (%) is calculated by dividing the number of successful checkouts by the number of checkout opportunities. I believe this statistic is already available through DartConnect but is rarely tracked.
Here are the Checkout Conversion Rate results along with the traditional checkout/double % from the first week of the 2018 Premier League in Dublin:
Whitlock clearly loses the most by going from Double % (7/8) to Checkout Conversion % (7/13). In fact, he’s the only one with a lower percentage. Whitlock hit his doubles, but he had several visits where he was on a checkout but didn’t get an opportunity at a double at all. Those kinds of missed opportunities don’t show up in the doubles percentage.
It was more common – at least on this night – for players to see an improvement when going from Double % to Checkout Conversion %. This makes sense because we’re not punishing a player for every missed double. We’re more interested in a slightly broader perspective on their finishing ability as a whole. Within this group, Gurney benefits the most from using the Checkout Conversion % (6/17) compared to Double % (6/22). Gurney missed more doubles but these missed doubles are “forgiven” if they occur during a checkout opportunity that is ultimately converted.