Here's the full list of hitters in MLB history with at least three 37-homer campaigns in their age-35 seasons or later: Barry Bonds, Rafael Palmeiro, Hank Aaron, Andres Galarraga, Babe Ruth and Nelson Cruz.
Meticulous in his preparation and greatly in tune with his body, the ageless Cruz has staved off Father Time for years, but as he enters his age-38 season and comes off a campaign in which his OPS dropped by more than 70 points, can the Twins expect Cruz to maintain his level of production?
First, the box score numbers: Cruz hit .256/.342/.509 last season, good for an .850 OPS and 135 OPS+ (adjusted for the league and the ballpark), down from a .924 OPS and 149 OPS+ in 2017. His average and on-base percentage dropped by more than 30 points each, and he slugged 40 points worse in 2018.
But the underlying Statcast™ metrics actually give reason to believe that Cruz wasn't all too different a hitter in 2018 than he was in '17.
Cruz has been a statistical darling since the Statcast™ era began in 2015. He finished in the top 1 percent of the league in hard-hit rate in each of the last three seasons, and actually saw his hard-hit rate increase from 48.7 to 51.3 percent in 2018, well above the MLB average of 34.2 percent.
His average exit velocity has been in the top one percent of the Majors in the last three years as well -- and that, too, increased from 93.2 to 93.9 mph in 2018. As for barrels, Statcast™'s metric measuring balls hit with optimal combinations of exit velocity and launch angle, Cruz has the second-most of any hitter since 2015, with 247, behind only J.D. Martinez's 251.

So, Cruz is still mashing baseballs at an elite rate. But has he gotten any worse at making contact?
Not really. According to Statcast™, Cruz is making contact on more pitches in the strike zone than ever (82 percent in 2018, up from 78.8 in '17), and his chase rate on pitches outside the zone and whiff rate have remained more or less level over the last several seasons.
Cruz actually posted his lowest strikeout rate of the Statcast™ era in 2018, at 20.6 percent, and has improved in that metric in each of the last three seasons. He's still walking at a healthy clip, too.
So, his at-bats don't seem to have gotten much worse, either. What, then, might have contributed to the decrease in his rate stats in 2018?
The one glaring discrepancy on Cruz's stat sheet in 2018 was his wOBA against the shift, which plummeted from .436 in 2017 to .285 last season. Opponents shifted on Cruz more than ever in '18, too. According to Statcast™, Cruz was shifted on by opposing defenses 19.3 percent of the time, up from 7.3 percent in 2017.
(That shift rate isn't actually extremely aggressive compared to other right-handed sluggers. Edwin Encarnacion, for example, saw shifts in 55.3 percent of his plate appearances, and even James Dozier, a former Twin, was shifted on 44.2 percent of the time in '18.)
Statcast™ also tracked a slight increase in Cruz's pull rate and a more marked decrease in his line drive rate, with matching increases in his ground ball and popup rates.
As a result, Cruz saw his BABIP drop from .315 to .264, meaning fewer of his batted balls were dropping for hits.
One season is too small a sample size to draw any meaningful conclusions about whether or not Cruz is actually changing as a hitter. But as far as Statcast™ is concerned, Cruz can still hit the ball with authority and with his standard contact ability from the middle of Minnesota's batting order.