Last week, Didi Gregorius launched his 20th home run of the season, achieving a feat that former Yankees great Derek Jeter never did: having back-to-back 20 home run seasons by a shortstop.
Over his career, Jeter’s peak ISO was .204, which he reached in 1999 after batting .349/.438/.552 with 19 home runs in 739 plate appearances. He also had a .334 TAv and 6.5 WARP- if you want a number that sums up his entire contribution.
Gregorius, however, has yet to reach an ISO above .190 (his current mark). Furthermore, he has yet to live up to Jeter’s ’99 hitter’s line – hitting .295/.328/.485 this season. Again, if we want to take TAv and WARP, he’s been hitting .285 and 3.6, respectively, in 498 PAs.
Then again, Gregorius has exceeded his 90th-percentile PECOTA projection, and over his entire Yankee career, has posted a 7.9 WARP – which surpasses Jeter’s numbers over the final seven years of his career. But, the caveat is that this is an arbitrary cutpoint that solely focuses on the declining years of Jeter’s career – past his age-33 season. Gregorius, however, has time on his side and could very well improve on his career season.
The question now would be: is Didi better than Jeter?
Starting with WARP, Jeter was worth 59.1 over his entire career. Gregorius, so far, has been worth 9.6 (16 percent of Jeter’s production). Even if we compare Jeter’s first seven seasons in order to produce a better comparison, Jeter still surpasses Didi with a 28.4 WARP.
What if we compare the transition period then? We take Jeter’s last years and plug in Gregorius seasons spent with the Yankees. Then we’re back at square one, Jeter produces 5.4 WARP while Gregorius has produced 7.9 WARP. While Jeter was better at the plate, his defense was so attrocious that it cost him points.
Gregorius, to his credit, is not a terrible player. He has an average bat and his defense is a vast improvement over Jeter’s. Nevertheless, he’d need to average 2.7 WARP over his next seven years to reach Jeter’s mark over his first seven years – something that seems unfathomable.
How about the bat? Over his career, Jeter had a .285 TAv – nine percent above the league average of .260 (which TAv is scaled to on a year-to-year basis). Didi is batting that this season, but over his career, he’s been exactly average! But, here’s the point in favor of Didi: over his career, Gregorius’ TAv has steadily increased. He’s gone from .228 in his rookie season to .285 so far in 2017. That’s a 25 percent increase that points to Gregorius trying to improve on the part of the game he finds more wanting.
But why such a big difference career-wise? If we look at Jeter’s hit types, by his age-26 season he had almost double the number of doubles and home runs than Didi currently has. Furthermore, though fairly arbitrary, Jeter had already reached 1,000 hits by the end of his age-26 season. If we are to take 2017 plus PECOTA’s projections post-2017, Didi would reach that mark by his age-29 season. Without the bat, Jeter’s production has had to been split across other positions – something that won’t bother the Yankees given how the Baby Bombers have fulfilled their median projections.
Finally, we get to the point of contention for Jeter. Those familiar with advanced defensive metrics know that Jeter was a below average defender. Nothing new here. So the question then becomes: how much better is Gregorius? Well between 2009 and 2014, Jeter produced a cumulative -75,5 FRAA, topping out at -23.8 in his final season (career-wise, Jeter has cost the Yankees approximately 30 wins).
Between 2012 and 2017, Gregorius has produced -11.5 FRAA. Overall, that’s an improvement of 64.0 FRAA, Gregorius is then, with his glove, costing 6 wins less than Jeter did; though he is still costing them some.
If we restrict Gregorius production to his Yankee years, then he produces -3.7 FRAA. Compared to the -303.6 FRAA that Jeter had as the Yankees everyday shortstop, this is a much needed defensive improvement. Jeter was always touted as an unimpeachable defender by sports pundits. We now know that his bat production was mostly negated by his glove. Gregorius, however, merely cancels out.
Despite this, Gregorius defensive chops allow him to edge out Jeter.
Sure, Gregorius will probably never live up to the hype that Jeter had. Jeter was the face of baseball for two decades and will surely be enshrined in Yankees lore with the likes of Mantle, Berra, and Ruth. Gregorius, on the other hand, will probably end up as a footnote on many a Yankees team until his contract comes up. And though he’ll never hit like the Captain, he is a defensive improvement over one of the most charismatic Yankees of our day.
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