The Red Sox and David Ortiz finally agreed to an extension, and it could be the final deal of Ortiz's career. He was already under contract for 2014, and this pact added a guaranteed 2015, with options for 2016 and 2017, when Ortiz will be 40 and 41 years old. Chances are good that he will either complete these four seasons and retire, or will finish his career during the extension either by choice or because the game finally got away from him.
That last part is basically unpredictable at this point: you can say you expect Ortiz to decline, and it could happen, but you won't look prescient. It's not exactly cracking a code to suggest players age, their bodies slow down, they get worse at their sport of choice, and then they retire. Even David Ortiz isn't immune from this. Ortiz has been so good for so long that the question isn't whether he'll slow, but when?
Most projection systems are no real help to us in terms of the future. Steamer and ZiPS only project the upcoming season, so we can just see that they aren't expecting him to decline in 2014, when they forecast lines of .284/.374/.506 and .296/.386/.552, respectively. ZiPS does have Ortiz playing in just 110 games amassing 472 plate appearances, though, that might have a lot to do with Ortiz's 90 games from 2012, the result of his season-ending Achilles injury, more than the fact he's 38. Regardless, they both still project him to be excellent in the short-term future, and it's difficult to disagree, given he just batted .309/.395/.564 and essentially was the Red Sox' offense in the World Series.
Baseball Prospectus' forecasting system, PECOTA, digs a little deeper, as it has both a long-term forecast and the percentile projections for 2014. PECOTA is the most pessimistic of the three systems for 2014, but still sees Ortiz putting up a high-quality campaign of .269/.359/.483 -- the most significant difference between that and the Steamer forecast is 16 points of batting average. We can also see high- and low-end projections for Ortiz, and these are where we can learn a bit more about what PECOTA thinks Ortiz's chances are to remain productive in 2014 outside of just that baseline forecast:
The 90th percentile forecast is the most optimistic, while the 10th percentile is the least. We can see that at the 90th percentile, PECOTA sees what is basically a repeat of Ortiz's 2013, where he had a .332 True Average (TAv). A five-win season from a 38-year-old designated hitter might seem unheard of, but we did just see one from a 37-year-old DH. There are scenarios where he's not quite that great, but is still a high-quality bat capable of four-to-five wins.
The lowest ranges might seem depressing, but consider this: PECOTA thinks the worst-case scenario for a healthy David Ortiz in 2014 is that he is an above-average hitter whose most significant fault is that he doesn't play the field. The worst-case scenario for David Ortiz is that he is simply as good as the rest of the designated hitters in the game: they produced a .267 TAv in 2013.
So, the three systems seem to agree that David Ortiz's chances of kicking ass in 2014 remain as high as they've ever been. The 2014 season isn't the one we're most concerned about, however: that was already happening regardless of whether he signed a new extension. It's 2015 and beyond that we have a real interest in, and PECOTA is nowhere near as optimistic in that regard.
In 2015, PECOTA forecasts Ortiz for 449 plate appearances -- enough to secure his vesting option for 2016 -- and a line of .245/.333/.428. That's a .274 TAv, better than your league-average designated hitter, but it's also similar to Ortiz's 20th percentile forecast for 2014. PECOTA is only willing to go out on so much of a limb for a 39-year-old slugger. Things are worse in 2016, where, during what would be Ortiz's vesting option season, he's slated to bat .240/.314/.404, worth less than a win, and worse than what the current average DH produces at the plate. PECOTA also sees a significant downturn in playing time, with 321 plate appearances.
If the Red Sox picked up Ortiz's final option for his age-41 season in 2017, PECOTA warns of a season in which Ortiz slugs below .400 and produces a line that's below the overall league-average, not just the DH one. It's still better than quite a few younger players could expect to do, but it's not anything like the Ortiz we know. That kind of season, at that age, might be the motivation Ortiz needs to call it a career.
It's worth remembering a few things about these long-term forecasts. If Ortiz is closer to his upper-level forecasts in 2014, his future projections would reflect that: these long-term looks are based on the idea Ortiz sticks to his baseline projection. Each subsequent seasons' projection becomes a little less (or more) depressing depending on how a player fills in the blanks in between the present and when those forecasts begin.
In addition, PECOTA builds its forecasts, at least in part, by using comparable players at the same age. Quick: name a few historical comps for 38-year-old David Ortiz, who is coming off of the sixth-best season ever for a 37-year-old per OPS+. PECOTA's comparables list includes the likes of the still-fantastic Frank Robinson, Edgar Martinez, and Frank Thomas, the still-great Rafael Palmeiro and Stan Musial, players finally giving in to their ages in Jason Giambi and Harmon Killebrew, and then players who suddenly lost it at 38 like Willie McCovey, Carlos Delgado, and Jeff Bagwell. It's no wonder PECOTA sees such a sudden drop in performance for Ortiz coming in the next few years: very few even make it to the point he's at, never mind continue beyond it successfully.
That's precisely why the Red Sox wouldn't lock him up for very long in the past, and why everything past 2015 is now an option of some sort. It's likely Ortiz's career will end when both he and his abilities agree it's time to go, but what happens in between this moment and then is unknown. He could succumb to injury and age like Delgado and Bagwell, soldier on productively but no longer great, or he could add himself to even shorter comparable lists in the future by continuing to be David Ortiz. All we do know is that whichever future it ends up being will come in a Red Sox uniform, and that's good enough for Ortiz, the Sox, and their fans.