Parallel Running: How to Validate a New Scoring System Against the Old One Before Cutover
When scores drive official results and money, you can't treat a new system as a leap of faith. The safest way to replace a trusted scoring system is to run old and new side by side, feed both the same inputs and only switch over when the evidence says you're ready.
Why parallel runs matter
Your current system, however dated, has years of edge cases baked in: tie-breaks, penalties, reruns, disqualifications and rounding rules that only show up a few times a season. A new system might pass every test case you write and still disagree on the one you forgot. A parallel run finds those cases with real data, before they matter.
How a parallel run works
Same inputs. Live scores and times go to both systems at once, through a splitter or a shared capture layer.
Old system stays official. The current system still drives payouts, scoreboards and broadcast. The new one runs in shadow mode.
Automatic comparison. A comparison tool checks every result, standing and payout between the two systems.
Discrepancy log. Every mismatch is logged with the inputs, both outputs and the rule involved.
Root cause and fix. The team decides whether the new system is wrong, or the old one was, and documents the answer.
Setting sign-off criteria
Agree on the go/no-go criteria before the run starts, so the decision isn't made under pressure. Examples:
Zero unexplained discrepancies in official results and payouts across an agreed number of events
All output feeds (graphics, scoreboard, web, stats) tested live in shadow mode
Failover and manual entry drills completed on the new system
Operators trained and signed off
Sign-off from operations leadership and the technical lead
Choosing what to shadow
Start with smaller events or early rounds to find issues where the stakes are lower
Include your edge cases, such as finals, ties and rule exceptions
Replay historical data where you have it, to test rules against past seasons
Plan around your season. Avoid starting a parallel run in your busiest weeks, and never cut over in the run-up to a major event
A typical multi-season rollout
For organizations with one main season, a realistic rollout often looks like:
Off-season 1: discovery, architecture and build
Season 1: parallel run in shadow mode
Off-season 2: fixes, final drills and training
Season 2: cutover, with the old system on standby
Shorter timelines are possible when integrations are simple, but don't trade away the parallel run to save time.
Cutover day checklist
Old system ready as a fallback for at least the first event
Every output feed confirmed against the new system
Rollback steps written down and rehearsed
Support team on site or on call
Code freeze in place
Related reading
FAQs
How long should a parallel run last?
Long enough to cover your edge cases and every output in live conditions. For many events, that's most of a season. The sign-off criteria decide, not the calendar.
Does a parallel run double the operator workload?
It shouldn't. With a shared capture layer, operators enter scores once and both systems receive them.
What if the old system turns out to be wrong?
It happens. Document it, agree the correct rule with officials and make sure the new system follows it.
Can we skip the parallel run if testing goes well?
We don't recommend it for systems that drive official results or payouts. Test data rarely covers everything a live season does.
Plan a safe cutover
Book a free 45-minute Tech Mapping Workshop. We'll help you outline a parallel-run plan that fits your season.
