The Royals’ wild 2024 bullpen leverage ride

Q spent the whole season figuring out whom he could trust.

The story of the Royals bullpen in 2024 was pretty simple - Lucas Erceg came in mid-season and immediately was the best guy, and the rest of the bullpen jelled toward the end of the season. This change bears out in the larger team performance. The Royals bullpen was 22nd in fWAR in the first half with a 4.21 / 4.14 / 4.57 ERA / FIP / xFIP line. In the second half, they improved to 11th in fWAR with a 4.00 / 3.54 / 3.89 line. Strikeouts were up, walks were down. Simple.

But they sure seemed a lot worse in the earlier part of the season, didn’t they? It felt like they were melting down here, melting down there, and melting down everywhere at the worst times. We can use leverage data to examine the meltdowns and see how things changed in the most visible, most important situations through the season.

The story is, again, pretty clear in the first half of the season. FanGraphs has a number of stats related to leverage. Take your pick of one. Their “Clutch” stat was near the bottom of the league and in “Awful” territory. They were dead-last in shutdowns and bottom-six in the ratio of shutdowns to meltdowns.

They were, indeed, doing a bad job in the most clutch situations.

In the second half of the season, they weren’t all that much better. Their “Clutch” stat was still in “Awful” territory, near the bottom of the league. But they weren’t dead-last in shutdowns! They went from 24th to 21st in win probability added.

That...doesn’t 100% match the narrative, does it? These stats aren’t really predictive, but I think it kind of lines up with ERA above. The actual runs being scored didn’t improve all that much between the halves, and these leverage performance stats are more about what happened. Not what will happen.

It wasn’t until September/October (regular season) that the bullpen really got going. The Royals bullpen was a top-5 unit then by pretty much any stat - fWAR, strikeouts, walks, ERA, FIP, xFIP, win probability added, and shutdown to meltdown ratio. Top-5 in all of them.

That month Kris Bubic and Lucas Erceg pitched the most high-leverage situations and were nails, but Daniel Lynch, Angel Zerpa, and John Schreiber also proved themselves in lower-leverage situations to give Q five guys to pick from in the playoffs. Minus Lynch, those four are the guys Q gave the most innings to in the playoffs (he subbed out Lynch for Sam Long).

The improvement was both addition and subtraction. I’ve created a graph that shows the ranking of each pitcher’s average leverage for each month of the season. Lower in the chart means higher average leverage. I’ve limited it to pitchers who threw at least 10 innings in the season. It’s essentially showing the trend line of how much Q trusted a guy before giving him the reins or blasting him into oblivion.

For example...Chris Stratton.

Q did not trust that dude any further than a sacrifice bunt.

Here’s Will Smith.

He was just thrown into oblivion.

Here’s James McArthur.

There were two sides to this leverage coin - worse relievers were getting fewer important situations. They were replaced not with average relievers, but above average relievers in Erceg & co.

It was really quite a journey to get there, but hopefully the re-addition of Hunter Harvey and new guy Carlos Estévez will give Q plenty of guys to pick from for high-leverage situations.