A number of comments yesterday wondered how last year’s prescribed Big Board projections mix performed vs. the rest of the projection systems, so here we go with a quick followup! Let me state right at the top - my projections mix evolves every year, and I recommend you use the newly calculated mix from yesterday’s post, NOT last year’s version. Projections have gone through a tumultuous few years with the introduction of juiced balls and statcast metrics, so our understanding is constantly evolving.
As a reminder, last year’s mix was:
Hitter Playing Time: 45% ZiPS, 30% ATC, 25% FGDepth
Hitter Rate Stats: 45% Steamer, 30% ATC, 25% ZiPS
Pitcher Playing Time: 60% Steamer, 40% Fans
Pitcher Rate Stats: 50% Steamer, 30% ZiPS, 20% PECOTA
See yesterday’s post for what all these numbers mean, but the R squared and RMSE values for each category were as follows:
So how does that rank?
On the hitter side, the correlations are better than any individual system did in 2018 - next best overall was Steamer, at 8% above average, and next best on a rate basis was ATC, at 6% above average. The RMSE is also better than all other systems, with the next best being a tie between several systems at 3%.
On the pitcher side, the correlation for playing time was somewhat poor, but it still manages to be second only to ATC overall, at 14% above average. I cannot overstate how much ATC just blew everyone out of the water on playing time projections last year. On a rate basis, my mix again beat all systems, with ATC next best at 6% above average. The RMSE is again better than all other systems, with the next best being a tie between several systems at 2%.