An Iota of xwOBA: Does Overperformance Enhance Confidence?

Paul Goldschmidt’s 2022 was a 12 months for the ages, actually: the Cardinals’ first baseman defied senescence to put up a 7.1 WAR and 177 wRC+, numbers which respectively tied for the Twenty fifth-best season amongst hitters 34 and older and the Fifteenth-highest amongst those self same elders with not less than 500 plate appearances since 1920. This 12 months, the slugger has largely picked up the place he left off, with a 164 wRC+ by means of his first 186 journeys to the plate. And in response to xwOBA, he’s been considerably higher than final 12 months.

In case you’re not acquainted, Weighted On-Base Average (wOBA) evaluates total offensive efficiency in a single stat, utilizing linear weights to measure the relative worth of every offensive final result after which placing that quantity on the identical scale as OBP. xwOBA, a product of Baseball Savant, combines a hitter’s stroll and strikeout numbers with a prediction for a way they need to have faired on balls in play based mostly on launch angle and exit velocity.

Last 12 months, Goldschmidt put up a career-best wRC+, however xwOBA was telling us that a few of that was smoke and mirrors: his .367 mark was properly shy of his precise wOBA of .419. That 52-point divergence was the fifth-highest overperformance amongst hitters with not less than 500 plate appearances in a single season for the reason that introduction of xwOBA in 2015. Entering his age-35 season and due for some regression, I dismissed the thought of one other large 12 months from the primary baseman.

Yet not solely is Goldschmidt’s wOBA above .400 once more, however his xwOBA has soared. In reality, previous to Monday’s tilt, he was under-performing it by 21 factors. Most of this is because of extra frequent exhausting contact: he’s raised his hard-hit price almost 10 factors to 55.2% and his barrel price a number of ticks as much as 15.2%, each Statcast-era highs for him. But a cursory take a look at his batted-ball profile (once more, previous to Monday) signifies that it’s unlikely a swing change is behind his mashing:

It’s attention-grabbing that he’s chosen this 12 months, shift ban and all, to put up his lowest pull price since 2015. Yet that is nonetheless a minor change; if something, it speaks to his exceptional bat management that his pull price vary has solely simply exceeded 5% over the previous 9 seasons, together with this marketing campaign.

Meanwhile, Goldschmidt’s common launch angle has dropped half a level, which explains the autumn in popup price and improve in line drives. But a look at his launch angle distributions tells you ways minimal this transformation actually is (with 2022 in crimson):

Perhaps he’s simply changing into extra acquainted with his new customized bat as he enters his second season with it. Or possibly the neatest participant Nolan Arenado has ever seen has continued tinkering in methods imperceptible to me. I wouldn’t be stunned if Goldschmidt noticed his xwOBA numbers from final 12 months and started working this offseason like he didn’t simply win an MVP. After all, he ditched the bat mannequin he’d used after 11 glorious large league seasons as a result of a biomechanics lab advised him to. In different phrases, he continues to evolve with the sport.

But a whole lot of hitters in all probability would have had a season like his and figured, why repair what ain’t broke, superior metrics be damned? Even for the anti-Goldschmidt, I questioned if a wOBA overperformance — relative to xwOBA — portended a future xwOBA improve just because improved confidence led to stronger underlying abilities.

While the discourse on overperformance relative to peripherals is ongoing, this obtained me excited about one other query: do stated overperformers have a tendency to enhance upon their peripherals over time? Whether resulting from a skepticism of their overperformance (and subsequent want for continued adjustment) or just extra confidence, this was seemingly the case for hitters final season. I cut up the common season into two halves, one comprising April by means of June and the opposite July by means of October. For the 218 hitters who had not less than 150 plate appearances in every half, a first-half wOBA overperformance correlated considerably with higher second-half wOBAs:

Or put one other means, gamers who overperformed their xwOBA by not less than 20 factors within the first half posted about the identical xwOBA on common, higher than those that underperformed within the first half by not less than 20 factors or those that have been roughly on par with expectations:

These are fairly small variations regardless of their statistical significance, and positive sufficient, once I ran the identical evaluation on 2021, there have been no important gaps. I additionally tried doing a year-over-year evaluation, changing first half and second half with your complete 2021 season in comparison with your complete ’22 season, additionally to no avail.

Then I attempted the identical evaluation with pitchers who had not less than 30 innings in each halves of the 2022 and ’21 seasons. There, I had the benefit of having the ability to use not solely xwOBA but in addition different efficiency evaluators and estimators like FIP, xFIP, and SIERA. In SIERA’s case, for instance, this meant that I may take a look at ERA overperformances relative to SIERA within the first half in comparison with SIERA enhancements within the second half. In 2021 not less than, first-half SIERA overperformers considerably lowered their SIERA within the second half, as did xFIP overperformers, however once I did the year-over-year evaluation, ’21 SIERA and xFIP overperformers had considerably worse marks in ’22.

Strangely, whereas the offensive surroundings in 2022 was considerably impoverished relative to ’21, peripheral-overperforming pitchers posted even worse peripherals within the former 12 months. In this case, maybe any improve in confidence or renewed effort to enhance upon underlying traits got here crashing down as soon as regression hit. But what about gamers who obtain a extra sustained confidence enhance by overperforming their peripherals again and again?

Consider Goldschmidt’s pal and teammate, Arenado. Since the arrival of xwOBA, his wOBA has outperformed the x-stat by not less than 20 factors every season till this one. At the beginning of this season, it appeared like his secret sauce had evaporated: in April, he posted a paltry .263 wOBA that really lagged behind his .268 xwOBA. Of 46 Arenado months on report (min. 50 plate appearances), this represented one among simply eight wherein he underperformed. But to this point in May, he’s rebounded in an enormous means by posting a .409 wOBA and a .403 xwOBA, shifting again into the constructive of wOBA/xwOBA differential and vastly enhancing upon his stats (each peripheral and in any other case). Perhaps an excellent higher instance of what I’m making an attempt to get at is Arenado’s 2022 season, wherein he posted a .359/.319 wOBA/xwOBA by means of June after which labored as much as a .403/.359 wOBA/xwOBA for the house stretch. This got here on the heels of a 25-point overperformance in 2021.

So I ran another check to unearth Arenado-like gamers, this time going again to hitters and the split-in-half 2022 season. Consider the next (the place “OP” stands for “Overperformer”):

These are principally small samples, and I needed to decrease the brink for overperformance to simply 10 factors with a view to get them even this massive. But they point out that a lot of the motive why overperformers improved upon their xwOBAs within the second half in 2022 was resulting from enhancements among the many subset of gamers who additionally overperformed their xwOBA in ’21. In different phrases: repeat prospects like Arenado, whose sustained overperformance outweighed any impending regression and in reality appeared to gas considerably of an enchancment.

Regardless of whether or not overperformance truly results in extra confidence or not (and the proof is actually combined), all of that is to say that what Goldschmidt is doing this season is extraordinarily spectacular. He didn’t get complacent like some could have after a profession 12 months, maybe even realizing that he wasn’t the type of hitter who may proceed to outpace his high quality of contact. And this time round, his features in that space are for actual. At 35 years previous, he in all probability gained’t proceed to put up career-best numbers going ahead, however his propensity for changes has him poised to stay productive for the foreseeable future.