Yuli Gurriel and the Age Effect

“Baseball is ninety percent mental. The other half is physical.” —Yogi Berra

Yuli Gurriel is a favorite for many Astros’ fans. He had many clutch moments over the years, particularly in the playoffs—which is something he surprisingly exhibited in the playoffs again this season. For me, he always seemed like a contact-oriented bat which complemented the power bats in the lineup. But there is no question that his batting results were not good in the 2022 regular season.

Gurriel will be 39 years old next year, exceeding the final age of most baseball hitters’ career. Given the past season’s performance and Yuli’s age, the Astros are faced with the decision whether to re-sign Gurriel for 2023. And that is part of the broader question of filling the first base position if Gurriel is not brought back, or alternatively returns, but in a more limited role.

I will focus on the age question. Over time, age diminishes all baseball skills, some more than others. But players adjust and continue to perform as they age—until the point is reached that they can no longer perform productively due to age-related decline. However, this point is reached at different ages for individual hitters, because players’ bodies, vulnerability to injury, physical condition, and batting style differ. Considering Gurriel’s age, it is fair to ask if his poor performance is a premonition of abrupt career-ending decline next season. If that’s not the case, then perhaps one can hope for some improvement in performance next year.

The answer to this question for Gurriel is obscured by the fact that his batting performance has alternated between years of good and bad performance since his age 35 season. Perhaps 2022 is a continuation of this pattern, and he can respond with a better year in 2023. But that is unlikely if it turns out that 2022 is driven by abrupt decline caused by age. Yuli’s wRC+ by age is shown below. (100 is MLB average offense, and w/RC+ above or below that reflects the percentage above or below MLB average.)

Gurriel: Age / wRC+

34 / 107

35/ 131

36/ 76

37/ 132

(2022) 38/ 85

In order to shed some light on possible performance at age 39, I examined the w/RC+ of first basemen who played at age 39. Using Fangraph’s leaderboard data, I selected all first basemen who played at least 400 innings between the age of 38 and 40. (This group includes Yuli Gurriel.) I removed batters who played at age 38-40 in the decades before the 1970s, mostly because comparisons may become more strained in the earlier era. A few batters (14%) in this group who retired before the age 39 season are also removed.

My analysis is confined to first baseman in order to maintain defensive comparability. Notably a number of players who were outfielders or third basemen were moved to first base for defensive reasons in the later years of their career. Below, I show the group of 24 players, displayed with number of games played, wRC+, and Increase or Decrease in wRC+ for the Age 39 season. This list is tilted toward very good players due to survivor bias, meaning that the players generally must have better than average baseball skills to continue playing at that age.

First Basemen At Age 39

(Name / Games / wRC+/ Change in wRC+)

Darrell Evans 151/ 121 / -18

Hank Aaron 120/ 177/ 29

Willie Stargell 125/ 137/ -24

Pete Rose 162/ 100 / -34

Carl Yastrzemski 147/ 105 / -10

Rafael Palmeiro 154/ 105 / -14

Fred McGriff 86/ 98 / -27

Willie McCovey 141/ 129/ -50

Tony Perez 84/ 99/ -5

Andres Galarraga 141/ 124/ -32

Jeff Conine 131/ 110/ 7

Jason Giambi 64/ 146 / 50

Rusty Staub 104/ 121 / 41

Ernie Banks 72/ 93 / 0

Tom Paciorek 88/ 82/ 10

Albert Pujols 131/ 90/ 2

Bill Buckner 79/ 38/ -30

Wally Joyner 53 / 75/ -20

Dave Bergman 87/ 62/ -48

Todd Helton 124/ 86/ -2

Jim Eisenreich 105/ 47/ -44

Mark Grace 66/ 44/ -46

Rod Carew 137/ 101/ -5

Ron Fairly 91/ 86/ -23

Norm Cash 53/ 109/ -20

Average for first basemen at 39:

Games Played 108

wRC+ 99

Change in wRC+ Since Age 38 -12.56

---

Observations

• Most players at age 39 were not used as full-time starters. On average, the 39-year-old first baseman played 108 games. The high was 162 games for Pete Rose and the low was 53 games for Norm Cash and Wally Joyner.
• The average wRC+ for 39-year-old first basemen (99) is slightly below the average MLB hitter. The highest is Rafael Palmeiro (154) and the lowest is Bill Buckner (38). The average wRC+ is as high as it is because several elite players (for example, Palmeiro, Evans, Stargell, and McCovey) normally play at such a high level of wRC+ that they can sustain significant age-related declines but still remain at a well above average wRC+.
• Now to the most interesting part of the comparison. On average, the 39-year-old first baseman experienced a 12.56 point decline in wRC+ from age 38 to age 39. This equates to a 10% reduction in the age 38 wRC+. Only seven of the 24 players in this group did not experience a reduction in wRC+ in their age 39 season.

Malcolm Emmons-USA TODAY Sports

My Conclusions

• The possibility exists that Yuli could return to average or better batting performance. After all, the average wRC+ for 39-year-old third basemen approaches the MLB average batting performance. However, more likely than not, he will be a below-average hitter next year. Only one quarter of the Age 39 first basemen experienced an increase in wRC+. And Gurriel would require a significant increase over his 2021 wRC+ (85) to achieve average (100). That said, it could happen...like it did in 2021 (75% increase in wRC+).
• If Yuli’s 2023 performance declined at the 10% rate suggested by the average for the comparable group, he would have a 77 wRC+ which probably is unacceptable for a starting first basemen. As I noted, an increase in Gurriel’s 2022 offensive performance is a distinct possibility, even though not the most probable outcome.
• If the Astros re-sign Yuli Gurriel, the plan for his use should be based on a more limited role than in the past. This would be consistent with the more typical 100 or so games for a 39 year old first basemen. A time sharing or platoon arrangement with another player from inside or outside the Astros’ system seems like the best way to reduce age-related risk.
• In 2022, Yuli’s “hard hit %” declined to the same rate as 2020 which is his worst wRC+ season. It is unclear if this is totally age-related. Hard hits tend to decline with age, but the trend can be erratic. If Yuli can improve his plate discipline, this has the potential to partially offset the decline in hard hit rate. Yuli’s 2022 O-Swing% is significantly above his career average and very similar to his 2020 rate. Yuli’s 2021 O-Swing rate was the best of his career and resulted in a 132 wRC+.

In summary, I don’t have the answer to the question posed at the beginning of the article. But hopefully this sheds some light on what 39-year-old first basemen have done in the past. I don’t know if the Astros should re-sign Yuli, but if the Astros decide to go a different direction, like most Astros’ fans, I wish Yuli the best of luck in the future. Yuli always will be viewed as an important cog in the Astros’ rise to prominence.