Last night, the Braves traded Andrelton Simmons to the Angels for Erick Aybar and a couple of pitching prospects. While it’s likely that Atlanta’s staff made this deal primarily to acquire Sean Newcomb, a big left-hander with high-end stuff and strikeout rates to match, I think it’s fair to categorize this return as surprisingly light. Newcomb is brimming with upside, but he’s still a pitching prospect who hasn’t yet figured out how to throw strikes on a regular basis, and has made all of seven starts above A-ball. He could figure things out and become an ace, or he could go the Archie Bradley path, where the stuff declines before the command gets better, and the Braves could end up with little to show for trading away the best defensive player on the planet.
But therein lies the rub. While everyone agrees that Simmons is a great defensive player, the Braves don’t appear particularly interested in betting on elite defenders aging particularly well. They balked at Jason Heyward’s salary requests in long-term negotiations, then traded him last winter, rather than keeping a 25 year old star outfielder around as a core building block. Now, for the second time in as many years, the Braves have traded elite defense in a young player for pitching potential, seemingly believing that it is easier to find a good defender with offensive question marks than a power arm who racks up strikeouts.
And as I noted yesterday, there might be some logic to that idea, given that there’s evidence that defensive skills peak earlier than offensive skills. The athleticism that allows a player to make plays that his peers can’t make is more vital for defensive value than hitting skills, and it’s possible (and probably even likely) that the Braves saw the potential for Simmons to lose value in the near future, if his defensive value dipped and his offense didn’t improve to offset the decline. So, it’s probably worth exploring how previous elite defenders have aged, and see if we can find support for the idea that the Braves were selling high before a coming decline.
To answer that question, we have to look at how the best of the best of the young defenders in recent baseball history have performed during the same stretch of their career as Simmons is headed towards. To find other players who have demonstrated similar levels of defensive value, I dumped our leaderboards into Excel and looked for players who racked up significant defensive value through their age-25 season. Given that we only have UZR and DRS dating back to 2002, but I wanted to look at a larger swath of players, I grouped players by their DEF value per 600 plate appearances; DEF is a combination of UZR and the positional adjustment for 2002-2015, and Total Zone and the positional adjustment for all years before 2002. Here are 10 players in baseball history (excluding catchers, who age pretty differently because of the nature of their job) who have compiled a rating of at least 20 defensive runs above average during the 18-25 portions of their career.
Unsurprisingly, most of these guys couldn’t hit; there’s usually an inverse relationship between offensive value and defensive value, and the best young defenders we’ve ever seen almost all forced their way into the line-up despite offensive limitations. The fact that Hal Lanier held down a starting job while running a wRC+ in the low 40s should tell you just how remarkable his glove must have been. On average, these 10 players combined for per season ratings (up through age-25) of -9 offensive runs per 600 PA and +24 defensive runs per 600 PA; this made them above average players, but ones where their value was heavily skewed towards the defensive side of the ball. At -12/+27, Simmons is slightly more extreme than even this group, but the group is, overall, a pretty good match for his early career performance.
So, how much of that defensive value did these players maintain after age-25? And perhaps just as important, what happened to their offensive performances from ages 26-30, which are the years the Braves would have controlled Simmons had they not made this trade.
Not surprisingly, every player on the list remained a well above average defender, and in most cases, were still among the best defensive players in the game, but note that they did indeed decline in defensive value as they gold older. The group’s average DEF/600 fell from +24 to +16, so they lost nearly a win per season in defensive value as they reached the years normally described as a player’s prime. While Mark Belanger bucked the trend, and Jim Sundberg was able to retain most of his fielding value, the majority of these guys saw their defensive performances drop off in their 26-30 years.
But because they were dropping off from such a high level, they remained valuable contributors even without historic defensive value, and it’s worth noting that their offensive performances did offset some of the defensive decline; the group went from -9 OFF/600 to -4 OFF/600, pushing them closer to the league average in terms of overall offense. Jim Sundberg made the biggest leap, going from being a hitter even worse than Simmons is now to an above average hitter during his peak, putting up +20 WAR during that 26-30 part of his career.
Overall, the group’s production barely moved at all; their +3.5 WAR/600 from 18-25 was almost matched by their +3.3 WAR/600 from age 26-30. They got better offensively and worse defensively, so they weren’t the same extreme kind of above average players they were earlier in their careers, but overall, they remained quite productive with a skillset that still leaned towards the defensive side of the ball. And it’s not like one guy is pulling up the average here; Lanier is the only one of these nine elite young defenders who bombed out as he got older, but his offensive performances were so poor that there’s no real reason to think Simmons is going to follow his path.
It’s worth noting that this aging curve almost identically matches what Dan Szymborski’s five year ZIPS projection for Simmons suggests. In the trade value series from this summer, where Simmons rated #30 overall, I noted that the forecast expects him to put up +17.5 WAR over the next five years, as it believes that he’ll decline slightly over the next few years but remain a +3 to +4 WAR player during the remainder of his contract. While it might be tempting to think ZIPS might struggle with extreme versions of defensive-value players, the other nine guys in history who played the field like Simmons early in their careers suggest that we shouldn’t expect a steep aging curve here.
And because I created an artificial cutoff of +20 DEF/600, we actually ended up omitting the guy who makes the best case for Simmons’ long-term value. Ozzie Smith graded out at +19 DEF/600 by Total Zone’s numbers in his 18-25 years, but then jumped up to +23 DEF/600 from 26-30, while also going from -17 OFF/600 to -5 OFF/600, turning himself from an average player into a star. Smith is the guy Simmons is most often compared to, given his elite defense and high contact rates, and it’s worth noting that he does provide precedent for some upside here. And it’s not just Smith, either; Terry Pendelton also rated at -18 OFF/600 and +19 DEF/600 through age-25, then jumped to +1/+11, so his offense improved more than his defense declined, and he got better as he got older as well.
Smith and Pendleton are at the top of a much larger group (29 players) that ranked between +15 and +19 DEF early in their careers, and as a whole, this group actually went through larger changes. As a group, they put up -6 OFF/600 and +16 DEF/600 from 18-25, so they were just less extreme versions of the bad hit/good field player, but from 26-30, these 29 players combined for +3/+3 ratings; they got a lot worse defensively, but got a lot better offensively, and so their WAR/600 went from +3.1 to +2.7, even with the big defensive drop-off.
So, yes, history suggests that Andrelton Simmons is going to get worse defensively in Anaheim, and we shouldn’t expect him to continue putting up +20 UZRs for much longer. But that history also suggests that the same trends that take some value from his glove should add some back to his bat, and that overall, Simmons should be expected to remain roughly as valuable as he has been to this point in his career. And that’s pretty darn valuable.
For the Angels, this looks like a pretty great deal, picking up one of the best shortstops in baseball for a couple of high variance pitching prospects, plus one year of Erick Aybar. For the Braves, well, I hope they’re right about Sean Newcomb.
Dave is the Managing Editor of FanGraphs.