Statcast Hitter Studs and Duds - xBA Analysis for Week 10

Death, taxes, regression. These are inevitable. Eschewing the first two topics, fantasy baseball managers may be interested in identifying batters who are experiencing regerssion, both positive and negative.

Once summer hits, we have enough data that season-long stats can be deceptive on the surface. That said, let's dive back into expected statistics with a look at expected batting average (xBA). Rather than simply scanning the leaderboard for those at the top or bottom, I'll look into rolling windows over the last 50 plate appearances to find recent risers and fallers.

All Statcast metrics are current as of May 30, 2021 and data/graphs are taken from BaseballSavant.mlb.com.

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Rolling xBA Risers

Rob Refsnyder, Minnesota Twins

+.138 xBA last 50 PA

I recently wrote up an article discussing late-age breakouts and the sudden proliferation of hitters age 27 and beyond blooming late. Refsnyder wasn't mentioned because he hasn't quite done enough to get the attention of fantasy managers but he's getting there. With Luis Arraez and Max Kepler hitting the IL, Refsnyder is sure to get everyday playing time. So far, he's made the most of it.

The 50-PA rolling window is a perfect way to evaluate Refsnyder since he's at 49 PA as of this writing. In his brief stint in Minnesota, he's slashing .364/.408/.568 with a pair of homers. Not only is his xBA up, but his xSLG has increased an astounding 310 points. Over his previous 50 plate appearances, he had hit .171 between Texas and Tampa in 2018 and 2020; he didn't appear in the majors in 2019.

A career .217 hitter entering this year, is this a delayed breakout for a former Yankees prospect or a temporary hot streak? I'd bet on the latter but he still has short-term streaming appeal and can slot in at multiple infield positions as well as the outfield.

Willy Adames, Milwaukee Brewers

+.124 xBA last 50 PA

Another case where a change of scenery has made for a big turnaround, except this time midseason. In the rare May trade, Adames was sent to the Brewers after posting a .197 average and K-rate over 30% in his first 142 plate appearances for Tampa in 2021. A second straight season of subpar defense with an Outs Above Average ranked in the fifth percentile was the last straw.

It's not as if the Rays don't have any infield prospects waiting in the wings to take his place. So Adames was unceremoniously sent shipping to fill the hole in Milwaukee's infield after they gave up on their own young shortstop, Orlando Arcia, at the start of the season. While Arcia hasn't been able to crack the Braves' active roster, yet Adames is adapting well to his new digs, raising his average 25 points in the course of two weeks including a four-hit performance against San Diego. His swing-and-miss issues won't disappear and he's not joining a great lineup but the park is more hitter-friendly. If only he could parlay his sprint speed into steals, his rising average could bring more fantasy intrigue but a career 13-10 SB-CS rate shows a complete lack of base-stealing instincts. Stream for cheap power while he's hot but don't expect him to become a season-long hold.

Lourdes Gurriel Jr., Toronto Blue Jays

+.83 xBA last 50 PA

Gurriel got off to a miserable start, slashing .224/.256/.316 in April. An early IL stint may have contributed to his struggles but it was still a jolt to his fantasy managers seeing as how his .308 average was among the league leaders in 2020. It took some time but he's turning it around. Since May 14, Gurriel is batting .417 and has seen his expected batting average rise to .278 in his last 50 PA over .199 in the previous 50. It would be nice to see him bat higher in the order on a regular basis but it's not likely. That limits his counting stats to some extent but Gurriel should still be plugged into fantasy lineups on a near-daily basis.

Rolling xBA Fallers

Josh Donaldson, Minnesota Twins

-.108 xBA last 50 PA

This is a perfect example of knowing when to ride the hot hand and when to cut ties. Donaldson was lighting it up early but has fallen on hard times recently. In his last 10 starts, Donaldson has a total of four hits, only one of which went for extra bases. A cursory glance at his Statcast profile makes it look like he's crushing.

His .267 xBA is above average and well above his career mark of .243 but doesn't tell of

Buster Posey, San Francisco Giants

-.134 xBA last 50 PA

It's safe to say the year off did him some good. Posey is posting a career-high .299 xBA that ranks among the tops in the majors right now. In fact, all his expected stats are in the 90th percentile or above and he's got 10 homers to boot. Not bad for a 34-year-old who hadn't played since 2019. The question is: will it last? He's certainly regressing to the mean.

He's falling as expected but this isn't a slump so much as a flaming bat just cooling down a bit. He's only gone consecutive starts without a base hit once this year and he hasn't done most of his damage in bursts, remaining remarkably consistent. Posey should remain in fantasy lineups everywhere.

Joey Gallo, Texas Rangers

-.139 xBA last 50 PA

Should we bother evaluating batting average with someone like Gallo, who we expect little to nothing from in that category? Since he's not among the league leaders in homers, it is important to determine if he's an asset or a liability in roto leagues. Will we get the 2019 version of Gallo who managed to bat .253 in under half a season or the one that hit .181 last season? It's not looking great, as he was down to .205 until a recent six-game hitting streak.

Although it doesn't seem he'll ever provide much in the way of average, we're getting the same Gallo we know and tolerate. The power has picked up recently and he should be fine meeting his ATC projection of 39 HR, 90 RBI, 84 R, and a .214 AVG.

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