Hurt Hitters are Outperforming Healthy Ones. Why?

I started diving into the dividing out the effects of injuries limited ramp time for the short season and didn’t get far. Some league-wide rates didn’t add up. Hitters who head to the IL are outperforming the healthy population.

Note: This analysis is math-heavy. I summarized my findings and questions at the end.

To start with, here are the league-wide OPS values for all nonpitchers as I compare the first month as players might have been ramping up.

It’s not that exciting of a table, but the key is to focus on the 2020 values compared to the previous seasons. The values and differences are consistently on the low side, but never the extreme value. The narrative surrounding the 2020 season was that “hitters weren’t as ready as normal” might have some legs but barely since the results don’t seem far off the norm.

With the above baselines, here are how hitters performed compared to their projection over the same seasons. I compared all the hitters’ projected and actual OPS values over the years and found the median and weighted (by PA) differences.

The median values are lower because teams don’t give struggling hitters the time to rebound. The difference was exacerbated this year with teams needing to win now with the short season and no minor league proving ground.

With the information I was wanting to find out of the way, I need to spotlight a possible major finding. It’s important but takes a little digging to find it.  Here are median and weighted values for players who went on the IL and those that didn’t

From previous work I have done, I’ve known that players who were on the IL underperformed their projections. That was true until the last couple of seasons. It wasn’t a quick change but it has been changing over the last half-decade. Here is the same information in an easier to read graph.

One item needs to be checked first. In 2020, a special mystery illness IL was created and it could cause possible complications. I decided to further divide the players on the IL by those who went on the special IL and those that didn’t.

The median difference is more negative while the weighted value is closer to zero. It seems like those who were able to return from the special IL for most of the season met or exceeded their projections. Those who didn’t play much struggled.

The regular IL values didn’t change much, so the trend sticks. But why?

Possible conclusions (if my math is right).

• For the past few seasons, hitters who have gone on the IL no longer underperform projections, but have outperformed them the past couple of seasons.
• Two possible reasons, that I can think up exist for this change. First, teams are better at getting hurt players to the IL (possibly linked to moving to the 10-day IL) and they make sure they are healthy when they return. Or teams can be stretching the IL rules and are putting healthy players on it. Maybe a combination.
• The regulars who returned from the special IL didn’t show any signs of struggling.
• If (big IF) the trend continues, fantasy managers don’t need to worry about hitters underperforming projections when they come off the IL.

That’s all for today. I’m still wrapping my head around what I discovered and how much it should influence my decisions going forward. Also, I need to run the same analysis for pitchers at some point to see if the trend continues extends to them.