The Post Game Carnage Report, specifically the Arena service, under the Stats section has a bool for isMatchOver, with the following info:
// Indicates if the match is completed or not. Some match details are available while
// the match is in-progress, but the behavior for incomplete matches in undefined.
“IsMatchOver”: “boolean”,
Has anyone seen an in progress match returned by the ‘Matches For Player’ service, which when queried would obviously result in a data set with ‘isMatchOver’ being false? I know the behavior is undefined, but I was at least hoping for an entry to get an idea of this “undefined behavior” :). So far I haven’t seen any show up while the match is still in progress.
Fingers crossed that down the line we have a match entry as soon as possible (prior to game start if I were to have my wishes granted).