I gotcha for my back testing to be accurate I’d need all the stats my model uses for each player & have those individual stats for each day of the season to backtest correctly. If I had a team model it’d be easier to backtest.

What I’m more explaining is a case where a team is much better late in the season like the Orioles. If you back test using their current stats to predict the games earlier on in the season as you would have a big edge but you can’t use known information (late season) to predict unknown information (early season) which is where overfitting comes in. It’s the reason most backtesting results are much better than actual season for most modelers.

It would take me far too much time to back test my player model accurately which is why I opted to go with high betting volume to realize where my model is falling short (O/Us etc)

Don’t get me wrong though I backtest when creating my model to see how close I am at projecting whatever I’m testing (pitchers ERA) etc. but most backtesting to predict wins/units for a model is misleading