RADIO
Hey RotoBallers, another Monday is upon us and it's time to make some decisions on who you'll start this week on your fantasy baseball teams once again. We are only a week away from the All-Star break, and if you're the type of manager who is looking at as much data as you can to try to get an edge, then hopefully there's something here for you in my new series - the bullpen report!
Maybe you're more into DFS or betting (that is the realm that many of you likely know me from) and looking for another angle when making your daily lineups and bets? I look at bullpen data every day when making those decisions and I think you should, too!
I started tweeting out some charts I have created with team bullpen statistics and got such a solid reception from the public, that I thought "this could be an article!" And after crunching a bunch of numbers late into the evening, I think I have come up with some info that you might find interesting! I'll walk you through my mindset in this article and explain what I think the significance of this data could be for fantasy baseball players, DFS grinders, and daily MLB bettors. Let's get right to it!
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Why Bullpen Data Matters?
It took me a while personally to come to the conclusion that team bullpen data matters and at the same time I realized that there was very little analysis of it out there available. I mean, that's why I wanted to write this piece, to try to shine a light on some data that gets little to no consideration from baseball fans, a group of people who are usually addicted to stats of all types.
Most bullpen-related content focuses on which relievers to target for saves, holds, and strikeouts. But this article is going to focus on bullpens as a whole, not individual pitchers. This idea was born when I started creating a number of different custom tables on Fangraphs that I was using every day as inputs for DFS and betting projections. But I really do think there is something for everyone, including seasonal fantasy baseball peeps here.
The rationale is simple. In today's game, starting pitchers are throwing fewer and fewer innings every season. Long gone are the days when guys like Curt Schilling would throw 300 innings and 15 complete games. Pitch counts matter more than ever and teams are often managing the innings of their starters to make sure they can hold up for an entire season (or postseason). Starters are pitching with max effort on nearly every throw (think guys hitting 98 MPH in the sixth inning or snapping off 20+ incredibly sharp sliders). And every team has 7-8 more guys sitting out in the bullpen waiting to come in and throw their best pitches at max effort, too.
So when looking at hitting match-ups, we always consider the opposing starting pitcher. I do everything from analyzing the hitter's and pitcher's platoon splits to breaking down the starter's pitch mix and how opposing hitters hit those pitches. The point is we have data (oodles of it) for all those matchups, but we are doing all of that work for two, maybe three at-bats. It's quite possible that each hitter will face a reliever for an additional 1-3 at-bats on any given night. And while we can't predict which specific relievers they will see, we can still analyze these macro trends to see which teams' bullpens are going to present them with better match-ups more often.
The Big Picture
Here's the latest version of what I had been putting out on Twitter. I have my five favorite stats for bullpens and both the season-long and last-30-day numbers for each. Remember the color-coding is from the opposing team's perspective so green means go (for hitters) and represents a bad metric for the bullpen. Red represents a good bullpen that is a poor matchup for opposing hitters.
I'm using xFIP as my ERA indicator here, but I think SIERA is pretty good, too, if you prefer it. Either way, I want a stat that we can use as an overall indicator of the bullpen's performance. WHIP does something similar and points us towards which bullpens are allowing the most baserunners. If you're hunting homers, then HR/9 is better than total home runs allowed since these bullpens have all seen very amounts of action in terms of innings pitched. This brings me to a new wrinkle!
The Last 14 Days
I had been mainly looking at full-season and a last-30 day rolling sample up until now. I wanted to zoom in a little closer and consider each bullpen's performance over the last two weeks, too. The season-long numbers don't move much one way or the other even with a good or bad week and a recent 30-day sample isn't likely to capture when a bullpen is really starting to trend up or down compared to their baseline performance.
What I was really interested in here was the total number of innings pitched. My working theory was that bullpens that have had to pitch more innings would be more likely to experience fatigue and therefore be more hittable. I tested this out by finding the correlational coefficient between innings pitched and xFIP for both the last-14 and last-30 day samples. The results were a positive relationship, although relatively weak with an average correlation of .27 between both data sets. Remember with correlation coefficients that a zero would mean no relationship and one would be the strongest. There is some statistical significance here in my opinion.
Looking Ahead
This is the pay-off for season-long fantasy baseball nerds and where you are rewarded for making it this far into the article. I pulled the schedule for every MLB team and ranked their match-ups for the upcoming week.
Once again, green means GO for hitters and lower ranks are better. Each bullpen was ranked from 1-30 with a ranking of 1 representing the best possible match-up for opposing hitters.
- Fatigue rank - this is simply calculated using the total amount of innings thrown by a bullpen over the most recent 14-day sample.
- Last 30 Day xFIP - every team ranked from 1-30 based on their xFIP over the last month.
- Overall xFIP - every team ranked from 1-30 based on their xFIP for the entire season.
Some takeaways here...
- The Yankees really stand out here with an elite match-up with Cincinnati and an above-average match-up with Boston. Not only have the Reds relievers been overworked lately, but they've also been pretty bad over the last month and all season.
- The Tigers hitters could be sneaky this week. Their offense has shown some glimpses of life lately, and Kansas City's bullpen has been one of the worst in majors all year, while the Guardians allowed the most HR/9 over the last two weeks.
- Not that you want to use any Angels' hitters not named Trout or Ohtani, but this next stretch is brutal as they will see both the Astros and Dodgers. Not only do those teams have elite starting rotations, but they also have rested top-notch bullpens.
Well, that's all I think I want to say about bullpens today. If you have any feedback or suggestions, I'd love to hear them and I hope this information can help you in some way, regardless of what format of gambling on baseball suits you!
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