Back toward the start of the 2022 season, I posted about how the Chiefs appear to be following the lessons of NFL aging curves when making personnel decisions. The typical progress of an NFL player through his career is to come in to the NFL with a need to learn professional technique and often with an opportunity to further mature physically. As they learn (and mature), their performance improves to a point where things click and they rapidly improve up to a point of reaching their peak. This peak in performance may be short or longer depending on how much improvements to technique can overcome the physical downturn brought by the wear and tear imposed by playing a collision-based sport like football as well as age. Eventually age catches up to everyone and the player's performance begins a steeper decline. Different position groups on average experience these career milestones at different times (table derived from the various sources I could find:
Note that these are averages, and everyone's different. Travis Kelce, for example, laughs at the normal tight end aging curve. Also note that these milestones are relative to the player's innate talent -- a journeyman at his peak will often still perform below a superstar in his decline. And let me express one more time just how awful the granularity is for the defensive position curves I could find -- I keep meaning to do the number crunching needed to define my own updated curves (for example, my own quick data crunching on top tight ends puts the tight end peak above age 26 rather than 25), but I just simply don't have that much time on my hands.
So what does this tell us about the current players the Chiefs need to make free agency decisions on? Let's go position by position. Most of these decisions will match up with conventional wisdom, but a few may differ.
Quarterback: Shane Buechelle, entering his age 25 season, should be expected to continue to improve (QB is the position that most depends on learning and mastering technique for success, so the peak tends to come much later than most), and considering they've protected him thus far, I'd expect them to definitely make an ERFA tender offer and have him on the active roster. Whether he's progressed well enough that they're comfortable having him be the primary backup for PMII is anyone's guess until they make an appropriate additional move either in free agency or the draft.
Running Back: Jerick McKinnon (entering age 31 season) is definitely at his decline stage, though I'd wager that his decline has been more gradual thanks to less wear and tear from his usage prior in his career. I'd expect them to offer him another short (one year) contract at a team friendly cost to see if he'd like to stick around and chase another ring. Ronald Jones (26) is theoretically at his peak, but given their use of him, I don't think they're seeing enough from him to warrant a contract that's significant in years or dollars, so I'd expect him to sign elsewhere.
Wide Receiver: Juju Smith-Schuster (27) is at his peak and is theoretically entering his decline with the coming season, so I don't expect the team to try to invest more than a year or two in him, but given how reliable he often was as a target for Mahomes, I could see them offering a short contract and leaving it up to Juju to prioritize another go-round or two in the Chiefs' offense or chasing more security (and probably more dollars) elsewhere. We forget how young Mecole Hardman (25) is, so I could see them offering him another multi-year contract to ensure the team has a wideout with a complete route tree next season. Entering his age 27 year, Justin Watson is what we saw of him, so while the Chiefs might offer him a short contract to keep him another year or two, I would expect them to try to fill his spot through the draft.
Tight End: Jody Fortson (28) is at his peak (though the conversion from WR and his many injuries muddy the waters quite a bit here), but I would think the Chiefs extend an ERFA tender to keep him another year. Blake Bell (32) is definitely in his declining years, and I think it's about time they try to bring in some new blood to join Gray and Fortson in backing up Kelce.
Offensive Tackle: OT is another position where the technical demands result in a lengthier period of rising performance, and believe it or not, that means Orlando Brown (27) should continue to improve. That, along with how well he played down the stretch and in the playoffs last season, should mean the Chiefs should be willing to offer him another long term contract and, if talks are unsuccessful yet again, tag him again. On the other hand, Andrew Wylie (29) may not have any more to show us, and I can't imagine the team making him an offer that would look attractive compared to what other teams that like (and pay) older linemen will offer. Finally, Prince Tega Wanagho (26) is definitely still solidly in his period of improving his technique, so it's a no-brainer to make the qualifying offer to an ERFA that they reportedly really like.
Offensive Guard: Entering his age 27 season, Nick Allegretti will probably not receive a substantial offer from the Chiefs to be a backup. I imagine he'll get more attractive offers elsewhere and leave.
Defensive Line: This is probably the least useful aging curve I have found since it lumps in pass rusher and run stoppers at both end and tackle all together. But it is clear given everyone's ages that Carlos Dunlap (34) and Brandon Williams (34) are definitely in their declines, Tershawn Wharton (25) is still in his rise, and Derrick Nnadi (27) and Khalen Saunders (27) are at or near their peaks. I'd expect Williams to not be made an offer to return. I'd expect Dunlap to perhaps get another one year contract offer. I'd expect at least one of Nnadi and Saunders to be given a (relatively short) contract offer. Wharton would normally be someone I'd see the team definitely bringing back given his promise as a young player, but his ACL tear will have an effect.
Linebacker: Darius Harris (27) is a little long in the tooth (in NFL years) to be a restricted free agent, because there's not much upside there. While they could tender him to keep him another year, I don't see them extending him, and they could just let him enter free agency and continue to build/maintain the linebacker corps through the draft.
Defensive Backs: Though not quite as messy as the defensive line curve, the DB curve does annoyingly group corners and safeties together, and it's apparent that a player will typically play at a high level at safety much longer than at corner before seeing skills decline. Still, you work with what you've got. Both Deon Bush (30) and Juan Thornhill (28) are theoretically in the decline stage, but I'm not sure if I buy the safety decline starting that early when removed from being mixed with corners. Still, I don't see Bush receiving an offer above vet minimum to play on special teams, and I can easily see the Chiefs moving on from Thornhill and drafting another safety to play centerfield for them.
Other free agents: There are no aging curves I've found for fullbacks or punters. However, I think we've seen that Andy Reid does not like changing fullbacks until absolutely necessary, so I can see Michael Burton (31) back for another season of very few touches but many special teams snaps. Tommy Townsend (27) is one of the top punters in the game today and still young compared to how long punter careers can be, though I question whether the Chiefs as currently constituted put a premium on having a great punter compared to the Alex Smith days when field position was really important. They may also want to eliminate the holding issues Dustin Colquitt has called out if they believe that is the problem.
Non-FA notes: Brett Veach has indicated he'd like to keep Frank Clark (30) around, but given his age, I don't see them trying to extend him very far or for very much, even if they can be guaranteed something like playoff Frank Clark for a couple more years. Chris Jones (29), given his level of performance, will be quite productive even when looking at several years of decline on a substantial new contract. I think the Chiefs go for that without question. L'Jarius Sneed (26) is still playing on his rookie contract, and I don't see them extending him -- instead, I think they'll let him play out his rookie contract to enter free agency and get himself a really nice contract elsewhere while they happily refill the secondary in the draft.