PAUL SWYDAN | STATISTICALLY THINKING
Numbers indicate decline may continue
Dustin Pedroia is a New England institution. In his first season, he was named the American League Rookie of the Year and helped deliver the Red Sox a World Series title.
In his second year, he was named the AL MVP. A couple of years ago, when Vita Coco launched a large advertising campaign, its billboards in New York featured Rihanna. But in Boston, Vita Coco correctly realized that not even a music superstar such as Rihanna can compete with Pedroia, who was featured on the billboards locally.
So, after his down season at the plate in 2014 that ended in injury for the first time since 2010, it’s only natural to wonder what version of Pedroia we will see next season.
Well, OK, not just next season, but the future in general. The 2014 season was the first of Pedroia’s new contract, which runs through 2021. And while he will be paid $12.5 million a season on the low end and $16 million on the high end during the contract — modest sums to be sure in the current baseball landscape — even for a team such as the Red Sox it’s hard to justify a $12 million bench player.
If Pedroia keeps declining offensively, he would be in danger of becoming a well-paid version of Mark Ellis. So, it’s instructive to take a look at how players age.
The general hitter aging curves developed by FanGraphs’ Jeff Zimmerman show that by his age-31 season, the average player stops contributing positive value on offense. Next year will be Pedroia’s age-31 season. Those curves take all players into account, however, not just the cream of the crop. Traditionally, Pedroia has been in said cream. But even if we isolate the aging curves to the players in Pedroia’s offensive range, things don’t look any better.
Zimmerman created a specialized aging curve for this story, based on Pedroia’s projected OPS in 2015. After posting a .712 OPS this season, both the Steamer and ZiPS projection systems peg Pedroia’s OPS to be in the same range — .767 by Steamer, .739 by ZiPS.
So, taking a sample of 162 second basemen, third basemen, and shortstops who were projected to have between .700 and .770 OPSs in their age-31 seasons, a sample of comparable players for Pedroia emerges.
A hopeful example would be Adrian Beltre. Heading into his age-31 season, which he spent with the Red Sox in 2010, Beltre was projected to post a .748 OPS. Instead, he mashed to the tune of a .919 OPS, and has more or less been at that level ever since. Part of that has to do with leaving Safeco Field, but a larger part was Beltre cutting his strikeout rate and making a point to hit more fly balls. Beltre found his fountain of youth and has enjoyed a career renaissance in his 30s.
While that’s the example to shoot for, overall things don’t change much in our new aging curve — the sharp decline in performance relative to projections starts in the age-33 season instead of age 31, but when it happens, it still happens quickly. One troubling example is Reds second baseman Brandon Phillips. Heading into his age-31 season in 2012, he was projected for a .762 OPS. His actual OPS ended up being slightly lower at .750. Then last season, at 32, his OPS dropped to .706, and then it fell again this season to .678. If he didn’t have three years and $39 million left on his contract, he probably wouldn’t be a starter next season.
Pedroia did endure a sharp decline this season himself, as he missed his projected weighted runs created plus (wRC+) — a stat that takes into account a player’s total offensive value while adjusting for ballpark, league, and year, and expresses it in an index form, where 100 is average, and 101 is one percent better than average — by 34 percent this season.
The players in the sample lost an average of five points of wRC+ from age 30 to 31, and after coming a bit closer to projections at age 32, began a steep decline shortly thereafter.
Things aren’t completely bleak, of course. Dan Szymborski, the creator of the ZiPS projection system, lists five comps for Pedroia in his projection this season, based on Pedroia’s 2011-14 performance, as well as a couple of other factors. Those five are Billy Herman, Pinky Higgins, Willie Randolph, Edgar Renteria, and Kevin Seitzer.
All of them played until at least age 34, and four of the five had at least one 120 wRC+ season left in them. On balance, these players declined, particularly Renteria, but they didn’t go quietly.
Renteria, as Red Sox fans would like to forget, is the cautionary tale. Three years after he left Boston, he was a 31-year-old playing in Detroit. He hit double-digit homers for the last time that season, going .270/.317/.382 with 10 homers overall, for an 84 wRC+ in 138 games. In his three seasons after that, with the Giants and Reds, he hit an even worse .256/.313/.345, for a 78 wRC+, with just 13 homers in 292 games.
Seitzer or Herman are more representative of the high end of the scale. Using Seitzer, as he is the more recent example, we find that at age 31 he posted a 102 wRC+, and then followed that up with 114, 115, and 123 the next three seasons, before bowing out at age 35 with an 82 wRC+ for the 1997 season. In fact, in his penultimate season as a 34-year-old in 1996, he posted his career-best full-season on-base percentage (.416). An example like that provides hope for Pedroia backers, even if Seitzer did retire at 35.
Another short-term ray of light for Pedroia should be his surgically repaired wrist. According to Zimmerman, who also runs an injury database, players with wrist injuries lose 15 points of Isolated Power — a measure that tells us how often a player hits for extra bases, and is most easily calculated by subtracting a player’s batting average from his slugging percentage — from one season to the next. Pedroia lost 16 points of ISO in 2014 vs. 2013, as he fell from .114 to .098. The American League average this season was .137.
In the season after, though, the same players on average see their ISO bump up 10 points, after accounting for aging.
While those 10 points are a nice bump, they’re not necessarily significant. In other words, Pedroia getting his wrist fixed isn’t a magic bullet — it doesn’t mean he’s going to get back to the 16-homer-per-season level he was at from 2008-12. The best predictor of future injuries is past injuries, and after two seasons with finger, thumb, and wrist ailments, it’s likely that these sort of injuries are going to be part of Pedroia’s game now.
Pedroia has been at least a three-win player in every full season of his career, eight in total. At FanGraphs, a three-win player, or 3 WAR, is considered a good player, with 4-5 WAR an All-Star and 6+ an MVP candidate.
In Pedroia’s MVP 2008 season, he posted 6.5 WAR, and his best season was 2011, when he posted 7.7 WAR.
But recently, the balance of his contributions has changed, as he has developed more prowess defensively as his offense slips. Our image of Pedroia will forever be him taking a whack at a fastball at his eyes — a pitch he has no business swinging at — and somehow lasering it over the Green Monster anyway.
Those moments have been harder to come by the past two seasons, and they may not be in great supply in 2015, either. Pedroia is still a very good player, but Sox fans expecting his offense to return to what it was are in for disappointment.
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