If X requires something around market rate for an extension, we are expecting 8-10 years right? As much as I like X and as much as it would pain me to see him go (as it did Mookie), do we really want to be paying him into his age 38-40 year?
Let's look at how many batters age 36+ qualified for the batting title over the past few seasons, and of those how many put up at least 2 fWAR.
- 2021: 6 qualified, 4 2+ WAR (Turner, Votto, Gurriel, Cruz)
- 2020: 4 qualified, 1 2+ WAR prorated (Cruz)
- 2019: 4 qualified, 1 2+ WAR (Cruz)
- 2018: 4 qualified, 3 2+ WAR (Zobrist, Cruz, Kinsler)
- 2017: 6 qualified, 2 2+ WAR (Cruz, Granderson)
- 2016: 7 qualified, 4 2+ WAR (Beltre, Ortiz, Beltran, Utley
- 2015: 8 qualified, 3 2+ WAR (Beltre, Ortiz, Rodriguez)
- 2014: 5 qualified, 2 2+ WAR (Ortiz, Byrd)
- 2013: 9 qualified, 5 2+ WAR (Ortiz, Hunter, Beltran, Soriano, Scutaro)
- 2012: 9 qualified, 7 2+ WAR (Hunter, Jeter, Soriano, Rodriguez, Scutaro, Suzuki, Konerko)
- 2011: 9 qualified, 2 2+ WAR (Jeter, Carroll)
On average over the last 11 years age 36+ players who qualified for the batting title averaged 1.68 WAR per season. Over the past 5 years, that number drops to 1.51.
That might not seem so bad, but keep in mind that this is emphasizing the best case scenario. We're looking exclusively at players who have managed to stay in baseball through their age 36 seasons.
I also looked at every player who put up at least 30 fWAR over the past 20 years to get a rough idea of X's peers. I looked at the point in each player's career after which they no longer consistently produced at least 2 fWAR per season. Most of these players never put up 2 fWAR season after their "fall off" year, but a few did sprinkle in one or two 2+ win seasons amid several sub 2 win seasons.
Among this group, there are four players that are age 36+, still active, and still producing: Nelson Cruz (41), Josh Donaldson (36), Justin Turner (36), and maybe Joey Votto (37). Interestingly 3 of those 4 were "late bloomers" that didn't really start performing at their top level until their late 20's, and the jury is out on Votto. He was good in '21 but had two crappy years before that. If his next few seasons are crappy, in hindsight his fall off year will be his age 35 season.
Of the players that are either no longer active or have already clearly reached their fall off points, the average fall off age was 34.42. Keep in mind that this stretches back to the steroid years, so there are quite a few players on the list that were aging in an era that was much friendlier to older players.
There are certainly some examples of players who were useful into their late 30's or beyond, like Big Papi, Chipper Jones, Jeter, Bonds, and A-Rod. There are many more cautionary tales of players that raked into their late 20s and fell off a cliff in their early 30s. David Wright, Miguel Cabrera, Albert Pujols, and Troy Tulowitzki all jumped out as cautionary tales. Two current players who haven't gotten old enough for me to put them on the list that raise concerns are Christian Yelich and Anthony Rendon. Yelich put up monster numbers from age 24-27 and has been mediocre in his age 28 and 29 seasons. Will he recover or will he be the next Carl Crawford? Rendon was great from ages 26-30 but last year he was way off. It's only one year, but surprisingly often great hitters just disappear in their early 30s.
Let's look at the attrition rate for 80 players who registered 30+ fWAR in the last 20 years:
View attachment 47219
Most players in this group are still productive through age 30, but then a period of sharp attrition follows until the mid 30's, where there is a brief plateau followed by a second period of sharp attrition. If a player is still productive at age 37, there's a decent chance that they will hang on for at least another year or two.
I'm sure that the Red Sox have better data than this, but I doubt that it shows a dramatically different picture. Time is brutal, even for elite players. Also keep in mind that my bar is set pretty low for productivity. Most of these guys were solid 4-6 win players for many years, so an expectation of 2 win seasons already represents significant degradation from peak performance. You do not want to be spending $30mm per year for 2 fWAR, although if you're getting 5 fWAR initially for several years it at least becomes more palatable toward the end of a deal.
But the fact of the matter is that even great players have pretty bad odds of producing at a 2 win clip into their mid to late 30's. If the Sox extend Bogaerts, there's something like a 25% chance that he won't even be producing at a 2 fWAR/year in year 3 of the extension. I'd give Devers an 8-10 year deal right now because there's a very solid chance that he's still putting up respectable results up until the very last years of that deal. Unfortunately I think the ship has sailed on Bogaerts unless he's willing to take something like 5/150 or 5/175, which I very much doubt.