Pittsburgh Pirates: Possible Expectations for Aroldis Chapman

CHAPMAN POSTED ELITE NUMBERS IN 2023

If one were to look at Chapman's Baseball Savant page, one would be quick to see that the Cuban lefthander is still among the best relievers in baseball from an advanced stats perspective. Of the 12 advanced statistics that Baseball Savant includes in their percentile rankings, Chapman was in the top 5% of the league in six categories; expected batting average, expected slugging, weighted on-base percentage, expected weighted on-base percentage, strikeout percentage, and expected era.

Against Chapman in 2023, hitters posted an expected slash line of .171/.258/.277. They also struck out 41.4% of the time, which ranked second among all relievers last season who recorded 50 or more innings pitch. The only reliever with a higher strikeout percentage was Baltimore's All-Star closer Felix Bautista at 46.4%.

The 6-foot-4, 235-pound Chapman also still records some of the highest whiff rates in all of baseball. In 2023, he recorded a whiff percentage of 42.2%, the third highest in baseball last season among all pitchers only behind the aforementioned Bautista and newly signed Los Angeles angel Robert Stephenson.

The expected batting averages and expected slugging percentages of opossing batters both ranked top 10 in baseball among both starters and relievers

Finally, despite posting a high barrel rate in 2024 (more on that below), Chapman is still posting a strong average exit velocity on batted balls. Last season, batted balls off Chapman averaged out at 86.5 mph which ranked 50th in baseball among 443 pitchers who faced 150 or more batters in 2023.

These of course are just a few highlights of Chapman's 2023 advanced stats. Other numbers to know include his 33% hard-hit rate percentage which ranked in the 87th percentile of all pitchers and his 47.7% ground ball rate which was in the 76th percentile of all pitchers.

AREAS OF CONCERN

If we're looking for downsides when it comes to Chapman, there are a few. For starters, hitters have adapted to Chapman quite well over the years, after posting chase rates of over 30% from 2015 through 2018, and another three seasons of over 25% from 2019 through 2021, the soon to be 36-year old has seen his chase rate drop to 22.5% and 23.4% over the last two seasons, which according to Baseball Savant ranks in the bottom 5% in baseball.

On top of the lower chase rates, Chapman still has quite a bit of a wild side, walking 14.5% of batters faced in 2023. In 58.1 innings pitched, he walked 36. His walk percentage was the third straight season in which he walked over 14% of batters faced. In his previous six seasons, he had posted just one season of walking 14% or more of all batters faced. Of all his concerns, this is arguably the most concerning.

Then there is the conundrum of being a power pitcher. Despite recording an expected slash of .171/.258/.277 against Chapman recorded a barrel percentage of 9.2%, the third highest of Chapman's career, an average of one barrel for every four at-bats.

Finally, there's the arguably the obvious concern.

Age.

Yes, Chapman posted quality numbers and very good advanced stats at 35 last year but every additional year makes it a little harder to meet those numbers. Can Chapman at age 36 continue to be a dominant reliever? As a power pitcher, if Chapman sees a dip in his velocity, it could be a season that goes south quite quickly.

That being said, there was no sign that his age was affecting him last season from a stuff perspective. The fastball is still there and the velocity is still very good. Last season, Chapman's fastball averaged 99.0 miles per hour and his sinker still touches 100 and 101 on a routine basis. He may not be throwing 103, 104, 105 like he did as a young 22-year-old with Cincinnati back in the 2010s but he still showed plenty of juice in his arm in 2023.

Notably, as last season went on for Chapman, he did have a few struggles including a six game stretch from August 21 to September 2 in which he pitched in six games, allowing five earned runs and seven total in 5.2 innings pitched. During that stretch he walked seven, hit one batter, and gave up five hits including two home runs.

Following that tough stretch, he finished the season allowing four earned runs in his last eight games pitched.

After the ups and downs of August and September, Chapman had a strong postseason for the Rangers, allowing just two earned runs across nine games and eight innings pitched.

WHAT ARE FAIR EXPECTATIONS?

So what are fair expectations for Chapman? Barring age suddenly catching up to Chapman, there are a lot of reasons to believe that flamethrowing Chapman can be another elite reliever for the Pirates bullpen in 2024.

Combining the upside of Chapman with the always reliable David Bednar gives the Pirates a menancing one-two punch at the back of the bullpen which will make any eighth and ninth innings intimidating for opposing lineups.

While Chapman will likely have a few bumps along the way, the soon-to-be 36-year-old should still be able to be one of the better relievers in all of baseball. What will likely separate him from being just good to very good or even elite will be his walks. Can he find a way to cut down his walks in 2024?

He's not going to cut it down entirely, he's always been wild but if he could cut his walk rate down from 14.5% to closer to 10%, that would be a huge boost for the Pirates but also would be big in Chapman putting together another strong season.

As of now, the Pirates should expect to get a mostly reliable Chapman who more often than not will be able to get the Pirates out of jams and be a consistent reliever, especially earlier on in the season. As the season progresses, it will be interesting to see how his workload affects him, as we saw his age slightly begin to show towards the end of the 2023 season for the Rangers.

If Chapman can cut down his walks as mentioned above, then Chapman could still very easily be an All-Star level reliever for the Pirates while creating a deadly back end of the bullpen alongside David Bednar.