First, let’s examine how each site views the Rockies side by side. The tweet below shows a graph that compares Fangraphs, Baseball Reference and Baseball Prospectus side-by-side for the past five seasons along with the average of the three sites for each season as well.
The first thing you should be thinking when you look at this graph is, “What was Baseball Prospectus thinking in 2015 and 2016?” The drastic differences in those seasons between them and Fangraphs/BR is one of the main reasons you should be looking at more than just one site. We’ll get more into the specifics of each site later, but BP’s formula is going to be more favorable to Rockies hitters while it also punishes Rockies pitchers. Here’s how it breaks down when you compare Position Player WAR and Pitcher WAR from each site:
It should be fairly obvious now that Baseball Prospectus LOVES Rockies hitters and viewed them in higher regards than every other site in each of the seasons chosen besides 2016. As for the pitchers, Fangraphs and Baseball Reference seem to vary from each other in how they assess Rockies pitchers but neither are as harsh to them as Baseball Prospectus.
When you combine them with Position Players WAR, the Baseball Prospectus total generally averages out to a more honest number and finishes closer to Fangraphs and Baseball Reference, but how it gets there can definitely look pretty wonky.