ZIPS and PECOTA – How ZIPS and PECOTA Are Different From Marcel and Steamer

In baseball, we often hear about a pitcher’s fastball having “zip,” which usually means that it’s high velocity and difficult for hitters to hit. Similarly, we might hear of a player wearing arm sleeves, which help to keep their arms warm and flexible. Arm sleeves are used in many sports, but they’re especially important for baseball players, since their throwing and catching arm must remain warm to avoid injury.

If you’re a fan of fantasy baseball, you’ve likely come across projection systems such as Fangraphs’ ZIPS and Baseball Prospectus’ PECOTA. These systems take a look at a player’s past performance and aging trends to develop future projections for them. They’re popular tools for analyzing and discussing a player’s true talent, though they have their limitations, particularly the later in the season you are.

One of the limitations is that a projection system can only project a player’s stats for the rest of the season, which doesn’t give much insight into a player’s long-term potential. Nevertheless, projections can be helpful in a number of situations, including scouring waiver wires for pickups or evaluating the value of a trade proposal.

Like Marcel and Steamer, PECOTA starts by calculating a weighted average of a player’s past performance (four years for most hitters and three years for young or old pitchers). It then identifies comparable players and uses their numbers to create projections. This approach is often more accurate than simply looking at a player’s career totals.