I haven't got a BA sub so I can't read the article, but I'm assuming the improved quality of player data, better coaching and the shorter runway are the three reasons. I'd also add that (outside of 10 year contracts) it's cheaper to put kids on the roster than 35 year olds playing out the string. If you're confident you know what you'll get, then every $1.5m you don't spend on a Jeurys Familia could cover part of the cost of running your minor league organization.

Does increasing pitcher velocity favor "young player skills" as the older players can't keep up with 96 MPH fastballs?

There are seven shortstops under the age of 23 who are in possession of a starting job: CJ Abrams (Nats), Gunnar Henderson (O's), Zach Neto (Angels), Anthony Volpe (Yankees), Elly de la Cruz (Reds), Masyn Winn (Cardinals), Ezequiel Tovar (Rockies). That's a lot! We're going to see some great shortstops over the next decade.

And Bobby Witt Jr just turned 23 in June.

And several more studs moving up through the minors or already knocking at the MLB door: Fangraphs #1 Jackson BAL in AAA at 19, #5 Lawlar ARI in MLB at 21, #10 Brooks Lee MIN in AAA at 22. It could be a golden age of middle infield defense for quite a while. I wonder if we'll get SI shooting another shirtless shortstop group shot in spring training one of these years.

(Was no one looking out for these guys? SI young Shortstops )

Bo Bichette a dinosaur as a 25 and 2/3s year old shortstop.

There are seven shortstops under the age of 23 who are in possession of a starting job

And the Padres put all their money in aging SS.

The new market inefficiency is $300m middle-aged shortstops.

At least in part because of the way we measure things against average, it's difficult to tell if we are in a "golden age of X" or not. At the moment, we seem to be in the age of position-less baseball (2023 tOPS+ by position):

C 90
1B 111
2B 98
3B 96
SS 95
LF 105
CF 99
RF 105
DH 106

Those are pretty trivial differences and especially that 2B, 3B and SS are essentially identical. Have teams found better ways to teach defense to good hitters or better hitting to good defenders? Or, in reaction to Ks and (full then partial) shifts, are they less concerned about moving decent bats with "below-average" gloves off of SS? If the last one then maybe we aren't in the golden age of SS, it's more that guy who used to be moved to 3B or 2B are now kept at SS. Are there <23-yo starting 3B, more or less than usual? Or, given some of those younger names are more glove-first, are we seeing a rush of young SS because teams are re-emphasizing defense after several years of full shifts?

SS tOPS+ vs 3B ... it seems the change to a universal DH has had a big effect on tOPS+ calculations ... for 2020 and 2022-23, every position is around 100; for earlier periods, most positions are usually over 100 while P are below 0 and PH (with many more PA) terrible.

2023 95 96
2022 96 105
2021 102 104
2019 103 110
2018 101 110
...
2013 91 106
2008 92 106
2003 91 97
1998 88 104
1993 89 104
1988 88 104
1983 87 108

So something definitely changed between 2013 and 2018 which is the period when the shift started to take off. The gap between SS and 3B used to be substantial but has narrowed to more 8-9 points with a couple of seasons of equity. A detailed look didn't narrow it down ... 2014 and 2017 were 10 point gaps, 2015-16 gaps were much larger.

Anyway, it could be a golden age of SS or a dark age of 3B or, in an absolute sense, teams are less concerned with SS defense and keeping hitters there longer.

Anyway, the gap between SS and 1B is about the same as the gap between SS and 3B used to be. We are also seeing fewer qualified batters which presumably means more multi-position guys (not particularly relevant to starting SS I don't think). It's probably as close to position-less baseball as the game has ever been (maybe in the very early days).