That’s a fun list of names, isn’t it? You have a hitting savant who was suspended twice for PEDs, one of the freest-swinging power hitters in recent memory, a Bash Brother who’s now best known for his inane/slightly depressing tweets, an upstanding Hall of Famer who was once hunted by a PI hired by George Steinbrenner, and at the bottom you have two of the biggest prospect busts of the last decade. Interestingly, only three players on this list were full-time center fielders (Jones, Wells, and Kostay). If that doesn't convince you Adam Jones is special, nothing will.





I defined "aging curve" as "percent of peak wOBA at each age", where a player’s wOBA is scaled to its 2014 equivalent. For example, Greg Luzinski recorded a .368 wOBA in 1973, his age-22 season. In 2014, this era of reduced offense, you’d have to put up only a .358 wOBA to match that. .358 is 89.2% of his peak (.401 scaled wOBA). So on a scatterplot of Luzinski’s aging curve, a point goes at (22, .892). Then I narrowed the list down to the four most comparable players by finding a line of best fit and seeing how the lines compared to Jones’s. Note that these numbers are not park-adjusted.





The results show that Adam Jones’s trajectory eerily matches Mark Kotsay’s. Here are their actual trajectories:





Jones and Kotsay both scuffled in their cups of coffee. Jones's second season was actually another cup of coffee, but he improved significantly. By Kotsay's second season he was a full-time player. Jones had a slow, steady ramp-up in production and since then has declined, while Kotsay peaked, fell back, and rose again. Both recorded their best season at age 26.





Here are their trajectories as fitted to lines:









It's uncanny how close the two are. I never would have guessed that of all the players in baseball, Mark Kotsay would be the best match to Adam Jones's career path. But three other players belong on this list. Vladimir Guerrero, Manny Ramirez, and Vernon Wells can all lay claim to a similar career path:









You can see how these three hitters, while similar to Jones, really have more in common with each other. And it's at this point I want to remind readers that we're looking at trajectories here, not raw offensive output. Manny Ramirez and Vladimir Guerrero were much better hitters than Kotsay, Wells, and Jones, even if they all progressed similarly.





Now the real fun begins. What did these players do from age 29 onwards, individually and as a group?









A few notes: I only looked at the average for ages when all four players were active to make sure I had the largest sample possible. I wouldn't put much stock in, say, Mark Kotsay at age 37 or Manny Ramirez at age 39.

Kotsay’s sharp drop in performance at age 31 was likely due to a back injury; he spent most of the season on the DL because of it. Also, he wasn't a regular player after age 30.

We don’t know how much of Ramirez’s line was due to performance enhancing drugs. He was busted in his age-37 season and again at the beginning of his age-39 season, whereupon he promptly retired.

Look at that crazy bounceback season Wells had at age 31! I bet that made J.P. Ricciardi, who'd given Wells a mammoth $126-million contract four years before, happy. But it was instead just an aberration in a decline phase and Wells was traded to the Angels . At age 33 he played about 1/3 of a season due to the presence of Torii Hunter Peter Bourjos , and some guy named Mike Trout Combining the average line with Jones’s peak (so far) gives the following wOBA values: Combining the average line with Jones’s peak (so far) gives the following wOBA values:

2015 (age 29): .330 wOBA

2016 (age 30): .322 wOBA

2017 (age 31): .310 wOBA

2018 (age 32): .310 wOBA

2019 (age 33): .306 wOBA

2020 (age 34): .299 wOBA

Remember, these values are scaled to the low run environment of 2014. With the coming pace-of-play changes and who knows what else, the run environment could change over the next couple of years. If anything, I would bet on the league average wOBA increasing, making these values worth less than they appear right now.

Jed Lowrie, Jordy Mercer, According to this methodology, Jones looks like a very good contributor in 2015 and a good one in 2016. Beyond that, he may be a slightly below-average hitter. It’s also around this time that we’re likely to see Jones move to a corner OF spot. Wells and Andruw Jones moved to a corner at age 32; Kotsay moved there at age 33. That’s troubling for Jones because his WAR will take a hit from playing a less-valuable position just at the time his wOBA slides into the .300 range. That’s the 2014 offensive output of players like Dayan Viciedo Yunel Escobar , the Birds’ own J.J. Hardy Salvador Perez , and Ben Revere. If you’re on this list and you’re not playing an up-the-middle position, your career may be in trouble.

But at that point, the Orioles ’ front office may not care because his six-year contract will be complete and it’s likely to be labeled a success. Jones gave the team outstanding production in 2013 and 2014 and he’s on track to deliver solid results in 2015 and 2016. It’s only the last two years, 2017 and 2018, where you could cast a skeptical eye at having him on the roster. And even then, he’s within shouting distance of being a league-average hitter, which is not a bad thing. Given the media and fan attention he commands, I have no doubt he’ll be treated well in these final years, and who knows, if he performs well enough the Orioles could keep him around after 2018.





Similar players taken from the Play Index at Baseball Reference; all other data from FanGraphs. Thanks to MGL for his aforementioned series and to Cy Morong for helping me brainstorm. Thanks also to Tom Tango for writing this.