MLB trends: Checking in on league’s stolen base rate, Cardinals need center-field help, and K.C. bullpen woes

We are more than two months into the 2024 MLB season and sample sizes are no longer small. Those early-season heatwaves are becoming legitimate outbreaks and the dips are becoming worrying signs of decline. With that in mind, here are three MLB trends to watch now that we’re well into June.

The sad state of center field in St. Louis

It wasn’t long ago that the Cardinals had more outfielders than outfield spots. As these things tend to happen, this “problem” resolved itself, and the Cardinals suddenly found themselves short on the outfield. Tyler O’Neill was traded, Dylan Carlson regressed and got injured, Jordan Walker still hasn’t found his MLB legs and Tommy Edman’s return from wrist surgery has been slow.

Edman’s slower-than-expected return and Carlson’s shoulder injury (he was hurt in a collision with Walker) meant prospect Victor Scott II left camp as an everyday center fielder. Scott may be the fastest man in baseball, he’s an electrifying runner, but St. Louis surpassed him at Triple-A and it showed. Scott hit .086/.139/.136 in 20 games before being returned to the minors.

Since the end of April, Michael Siani has been the club’s everyday central defender and, although he is a talented defender, he has not managed anything. Siani’s biggest contributions to the offense are his MLB-leading eight sacrifices. The Cardinals claimed him off waivers from the Reds last September and now Siani has been placed on daily duty. That’s the state of center field in St. Louis.

Between Scott getting beat and Siani not doing much other than catching the ball, the Cardinals have the worst center field production in baseball this season at -0.8 WAR. The Dodgers and Rangers are a distant second worst at -0.2 WAR. Offensively, the center field outlook in St. Louis is bleak. Here are the worst central fields offensively:

It was a tough fall for Cedric Mullins in Baltimore, and that Aaron Judge guy is pretty good, but yeah, the Cardinals center fielders have been the least productive center fielders in the game, and one of the least productive positions in the stretch. Only the Red Sox second basemen (30 OPS+), the Tigers shortstops (33 OPS+) and the Marlins catchers (33 OPS+) have been worse offensively.

Carlson has gotten a few starts in center field in recent days and could see more time there, though he posted a .175/.277/.211 line in Tuesday’s game and has an 88 OPS+ since finishing third in the NFL’s Rookie of the Year voting. NL in 2021. Not sure he’s a solution at this point. There is still no defined timetable for Edman’s return. Recently, he started swinging a bat, and that’s about it.

The Cardinals started 15-24 and have since gone 16-10, putting them firmly in the wildcard mix. The negotiation deadline is seven weeks from now. With Edman’s status uncertain and Scott needing more minor league experience, center field help should be at the top of the deadline shopping list. Finding even a league average center fielder (old friend Harrison Bader?) would be a huge upgrade for the Cardinals.

Kansas City’s low-hitting bullpen

At 39-29 and with a run differential of over 65, the Royals are one of the biggest surprises in baseball this season. They spent some money in the offseason (Seth Lugo, Michael Wacha, etc.) and have young talent on the rise (primarily Bobby Witt Jr., but also Maikel Garcia, Vinnie Pasquantino, Cole Ragans, etc.), and the result is a team which looks nothing like last year’s 56-106 team.

A postseason berth is within our reach and there is one part of the roster that the front office must attack at the deadline: the bullpen. The Royals relievers rank 20th in ERA (4.25), 22nd in WAR (0.6) and 24th in win probability added (0.10) this season. They also rank last in strikeout rate: 18.0% of batters faced. The MLB average for relievers is 22.8% (the lowest since 2016!).

Not only do the Royals have the lowest bullpen strikeout rate in baseball this season, they also have the lowest bullpen strikeout rate of any team in nearly a decade. Excluding the 60-game pandemic season in 2020, here are the last five bullpens with a strikeout rate of 18% or worse:

• 2024 Royalty: 18.0%
• Tigers 2015: 18.0%
• Gemini 2015: 17.9%
• 2014 Gemini: 17.3%
• Astros 2013: 17.5%

The 2013 Astros came as close to losing on purpose as any team, and the mid-2010 Twins teams were behind. They chased quick exits on the floor. Minnesota finally got smarter and realized that the best teams miss bats, and that strikeouts are key in the late innings. Nothing bad can happen when you don’t allow the ball to be put into play in close games.

Royals starters have a 23.0% strikeout rate, the 12th highest in baseball and comfortably above the league average of 21.9% for starters. The strikeout issue is limited to the bullpen and is something Kansas City should try to correct at the deadline. I mean, they need to improve their bullpen in general, but specifically they need bats. They allow a lot of balls in play in the late innings.

Checking MLB Stolen Base Rate

Last season, MLB implemented several significant rule changes, most notably the field clock and indoor travel restrictions. It also introduced rules designed to promote stolen bases and more aggressive base running in general. Base running is exciting and MLB wants more. To achieve this, they installed larger bases and limited pitchers to two releases per plate appearance.

The rule changes worked as expected. The league has stolen 3,503 bases in 2023, the most since baserunning’s Wild West days of 1987 (3,585 steals). It was the first year with 3,000 steals since 2012 (3,229). The league’s 80.1% stolen base success rate was a new record and not by a small margin either. The previous record was 75.7% in 2021.

How would players and teams address stolen bases in Year 2 of the new rules? Would they attempt more robberies? Would pitchers and defenses be better than preventing them? Now that we’re about 40% into the regular season, we’re starting to get some answers. Here are the basic stolen numbers that come into play on Tuesday:

The stolen base attempt rate is attempts per stolen base opportunity, with a stolen base opportunity defined as a runner on first or second base with the next base unoccupied. The league’s average attempt rate has hovered in the 4% to 5% range for a long time. Now it’s approaching 7%, so yes, when runners have the opportunity to steal, they are trying to steal more often with the new rules.

Attempts are up and success rate is down from last season, even though we are seeing almost exactly the same number of steals per game. The increase in attempts and the decline in success rate have plateaued so far. We’re talking small changes here – one more attempt every 250 opportunities and one more steal every 55 attempts, give or take – but changes nonetheless.

Steals per game, success rate, and attempt rate all increased as last season progressed. I’m sure part of that was because runners learned the new rules and figured out exactly how far they can take things, although we’ll have to check back in a few months and see if there’s another spike in stolen bases during the season. Just like home runs, there are more steals in the summer months.

For now, steals per game are in the same range as last season. A few more attempts and a few more caught steals, but not a massive shift in one direction or another. I was curious to see if there would be even more attempts this year now that players are familiar with the rules and how to take advantage of them, but that hasn’t happened yet.