The Best and Worst Bullpens for Daily Fantasy

It’s not my day to do the daily fantasy post, but I want to touch on a daily fantasy strategy thought today. It occurred to me that when looking at the best matchups for hitters each day I only look at the starting pitchers the hitters will be facing, but relievers have thrown just over a third of all innings pitched this year. The starters are obviously the more important factor, but it could be informative to know who the best and worst bullpens are. The quality of the bullpen will never be a determinative factor, but it can be a plus or minus just like weather or ballpark can be.

The biggest issue was figuring out what was the best metric to look at to see which bullpens are best and worst. Since I’m doing this for DFS purposes, I considered calculating either the fantasy points accumulated by bullpens or the fantasy points allowed to opposing hitters. But those numbers would be influenced by the quality of the team’s starting rotation. Because innings pitched are one of the main ways pitchers accumulate positive points, the “best” bullpens by that measure would be the ones who pitched the most. But they wouldn’t necessarily be the best, they’d be the ones with the starting rotations that pitched the least.

Then I considered looking at ERA, K-BB%, xFIP or even all three, but I ultimately decided that might not have a direct enough relationship with fantasy scoring. So I doubled back to calculating the number of fantasy points accumulated by bullpens but then dividing by the number of innings pitched to negate the impact of the quality of a starting rotation. I’m leaving out innings pitched when calculating point totals for bullpens and just looking at the points gained or lost in the categories the pitcher can control (for the most part): strikeouts, walks, hit batters, hits allowed and earned runs allowed.

 

For the most part, these numbers match up well with what ERA, K-BB% and xFIP would have told us about these bullpens. It’s interesting to note that all six teams on the right side of the image have home ballparks with a basic park factor this year that is neutral or better for hitters. And three of the four teams on the left side of the chart have a home ballpark that plays favorably for pitchers. And not that you needed another reason to start hitters at Coors Field, but here’s another one.

To take this one step further, let’s see if there are any differences in how bullpens fair against hitters of a certain handedness. I try to utilize the platoon advantage as much as possible, so it could be instructive to know if a hitter has both the platoon advantage against the starting pitcher and a favorable matchup against the bullpen. Of course, managers are much more likely to match up relievers with specific hitters to neutralize the platoon advantage, but looking at bullpens with this split in place could help us identify teams that aren’t able to match up as well.