How Weird Is Alex Rodriguezs Resurgence

Darrell Evans198740150340.23 Moises Alou20063998220.22 Barry Bonds200641130260.20 Jim Thome201039108250.23 Carlton Fisk19884076190.25 Barry Bonds200439147450.31 Raul Ibanez201341124290.23 Cy Williams192739131300.23 Andre Dawson19943975160.21 Willie McCovey197739141280.20 Willie Stargell197939126320.25 Steve Finley200439162360.22 PLAYERYEARAGEGAMESHOME RUNSHOME RUNS PER GAME Hank Aaron197339120400.33 Barry Bonds200742126280.22 Hank Sauer195740127260.20 Ted Williams195839129260.20 Once–disgraced slugger Alex Rodriguez turned 40 years old Monday, and he’s still hitting home run hat tricks. His remarkable return to form (at the moment he’s a top-10 hitter despite missing all of last year) has even New York fans who loathed him not long ago mulling his redemption.So just how good, just how unexpected, just how amazing is this season of his?From at least some angles, very. His 23 home runs through 97 Yankees team games (as of Sunday) put him “on pace” for around 38 for the year, which would leave him trailing only Barry Bonds in 2004 (45 HR) and Hank Aaron in 1973 (40 HR) among players who started the season age 39 or older. Even assuming Rodriguez can’t keep up that pace and regresses toward the mean a bit, he seems very likely to end up in the top five all time for his age — he needs only 10 more home runs to clear that threshold.If his season ended today, his home runs per game played would already be cream of the crop. Here are the top 20 HR/game averages for players 39 and older with at least 75 games played: Ted Williams196041113290.26 Alex Rodriguez20153990230.26 Andres Galarraga200039141280.20 Hank Aaron, Barry Bonds, Ted Williams … Alex Rodriguez. That’s amazing company.Looking beyond home runs, Rodriguez’s numbers are still excellent, but not quite as historic. Among other players starting their season age 39 or older who had at least 100 plate appearances, his 0.73 wins above replacement (offensive WAR)1Baseball-Reference’s version. per 100 plate appearances is 32nd all-time.Let’s compare Rodriguez to players who played similarly well (or better) into their late 30s2The chart shows all players since 1900 who had at least four seasons with 100-plus plate appearances after age 35 and who accumulated a total of at least 8 offensive WAR over that season. (Rodriguez has 8.7.) Oh, and they also had to average at least 0.5 per 100 plate appearances, by season. (Rodriguez has averaged around 0.6.) I’ve also excluded later seasons from this average for those who played more than five seasons past 35, to avoid filtering out players who had great careers into their late 30s but stuck around too long.:As we can see, the three main “peaks” are Babe Ruth, Williams and Bonds (unsurprising). But Rodriguez’s twilight career, even counting this season, is still fairly mainstream (so far).Rodriguez’s dramatic-seeming improvement this year really isn’t that unusual either — probably worth noting given suspicions stemming from his history of performance-enhancing drug (PED) use. Rodriguez has jumped 0.3 wins per 100 plate appearances from the last season he played to this one. That’s good, but it’s only the 53rd-largest such jump among those 39 and older (compared with 134 declines greater than 0.3).3The ratio of declines to gains of this magnitude is actually much smaller than I would have guessed. That is, he’s no Gavvy Cravath, who went from a .696 OPS (on-base plus slugging) at age 37 to a 1.078 OPS at age 38.Indeed, playing deep into one’s 30s (and even beyond) has gotten much more common (though the increase is a bit less pronounced in Rodriguez’s 39-plus age group):It’s interesting that Rodriguez is somewhat bucking the recent downward trend, one that seems to have started around when MLB began cracking down on PED use (a speculative causal connection, but one that’s highly likely, in my opinion).4As for what might have happened in 1987, I asked FiveThirtyEight’s Rob Arthur, and he didn’t have any great ideas off the top of his head, either. If you do, please let us know. With the departure of players like Bonds — who couldn’t find a job in 2008 despite having 1.045 OPS in 2007 (higher than Mike Trout in 2015), baseball has lost roughly half its number of batters 35 and older since 2007.In other words, one of the more remarkable aspects of Rodriguez’s season is that it’s defying a trend that likely results from league efforts to end PED use, the very thing that helped make him so good before — as well as such a pariah later.CORRECTION (July 29, 6:06 p.m.): An earlier version of this post misstated the seasons in which Rodriguez played. He did not play last season, so his increase of 0.3 WAR per 100 plate appearances was from 2013 to this season, not from last year to this one. Willie Mays197039139280.20