[sklink]

There is no access to MMR from the Steam API. Best we have is Normal, High, and Very High skill splits and the problem then becomes having a large enough sample size to have accurate results.

114 heroes that all influence each other when they play together so if you're looking at matchups for two heroes that don't get played frequently the accuracy is already limited.

That said, my strength is in front end, not statistics. Getting a Normal and High split might be fine as is.

[thenomad]

True, but the OpenDOTA API does give access to estimated MMR stats for many games, which are pretty accurate. So you could use those if you wanted to.

That would limit the available match pool, granted. It depends on how many thousand games you need to make predictions, I suppose. I was able to pull some interesting data a while back from the 2k pool but I wasn't trying to solve as hard a problem as a global hero picker.

[sklink]

They do, but they don't allow sequential pulling of match data.

I would have to collect my own data and poll their API with each match id to get the MMR estimate.

Although that works in theory, their API rate limit is 3/s and last time I checked there were about 1M matches / day (~12/s) so we couldn't keep up.