Post All-Star Break wOBA Overperformers and Underperformers

The crux of the fantasy season is looming, and decisions need to be made as we push to the playoffs. In one league currently, my shortstop position is in need of a jolt, and with a playoff spot already secured, time is running out to get aggressive and make a move. While Otto Lopez and Colson Montgomery have served me well for the majority of the season, the data is saying an aggressive move is required. Lopez, whose bat was running hot pre-All-Star break, has cooled, and even his .259 xwOBA says the bat isn’t good enough to wait on at this stage of the season. And Montgomery has no luck gap at all, with his results matching his .237 xwOBA.

So now to look at the hitters who have been the most unlucky and lucky since the All-Star break. Who can we target and who should be dropped based on expected data? I have included the BABIP in the tooltip if you hover over the players’ dots so we can see if luck has played a factor in the underperformance or if it’s warranted. Below the chart, we can see the full list of top 10 overperformers and underperformers, and they have been highlighted in the chart. Without going in depth on all 20, I will discuss some noticeable trends that have developed post-All-Star break, and hope this chart can assist with your own rosters.

Regression in Boston? Tide Turning in Milwaukee…

Following their 15-game winning streak in July and a 9-game winning streak going into August, Boston was able to propel itself back into the playoff race. They have since cooled and have won just 2 of their last 8 games following a win in Pittsburgh. When looking at their wOBA comparatively to what was expected, this drop-off was coming, and something will have to give for a sustained push in September. Five hitters have overperformed since the break, three of them in the league-wide top 10, and their output is worth monitoring if you rely on any of these Boston bats.

Ceddanne Rafaela, +.087 (.326 BABIP)
Caleb Durbin, +.085 (.349 BABIP)
Andruw Monasterio, +.061 (.409 BABIP)
Willson Contreras, +.032 (.349 BABIP)
Masataka Yoshida, +.022 (.301 BABIP)

For those rostering Wilyer Abreu or Jarren Duran, they have actually underperformed expected data and should continue to improve on their already strong summers. Abreu in particular, almost inexcusably running a .188 BABIP and a .380 wOBA/.398 xwOBA. But I guess that’s what happens when you have 10 home runs in 27 games, and a HR/FB rate of 21.7%. On the potential add side, despite a clear overperformer, Monasterio is a player available on the majority of waivers, but regression is inevitable. His .061 gap between results and expected, on a .409 BABIP, suggests it won’t hold, but given his xwOBA is still a respectable .340, maybe he could offer a solution to my Lopez, Montgomery problem, if just for the short term. The power numbers have fallen off a cliff in August, with his SLG dropping from .631 in July to .395 in August, and ISO from .292 to .070. But he has still gotten on base at a similar rate, dropping from .413 OBP to .404 in August.

On the reverse side, we have the Brewers, who have won just 1 of 5 before getting back-to-back wins in LA, their overall performances suggest they should continue to bounce back from that minor slide and are well primed for a strong end to the season. Just as Boston has three of the ten overperformers, Milwaukee has three of the ten underperformers. Four of their six qualified hitters have posted a wOBA below what their expected numbers say they’ve earned. Christian Yelich (-.062) and William Contreras (-.057) lead the group, both producing well beneath their contact quality, with Contreras’ .167 BABIP pointing to how little has fallen in for him given his xwOBA is above .300. Garrett Mitchell sits in a similar spot at -.056.

Mirrored Rookies

If you happen to be one of the lucky ones rostering Kevin McGonigle or JJ Wetherholt, their second-half data is pointing in opposite directions, and could matter for your playoff lineup decisions. While these two are future superstars, an interesting mirroring has emerged since the break. Kevin McGonigle has overperformed by 66 points, a .358 wOBA on a .291 xwOBA and a .317 BABIP. JJ Wetherholt has done almost a mirrored opposite: a .290 wOBA on a .354 xwOBA, his .197 BABIP holding him 64 points below expected.

Looking into their squared-up rate over the season as a whole, Wetherholt’s recent misfortune really shows given how good and how consistent a hitter he’s been this year. He has been able to square the ball up much more with the ideal launch angle, and consistently without recent reward, more so than McGonigle. He is an obvious everyday starter, but worth noting how good his underlying profile is, as one of the best second basemen in the league, for 2027, even compared to a hitter as well-rounded as McGonigle.

McGonigle has not been as consistent, perhaps surprisingly, in the squared-up department compared to his rookie counterpart, but has already proven himself to be one of the best hitters in the American League, even if he has ridden some luck this second half.

Final Thoughts

To come full circle back to my own example of my shortstop problem, now is the time to make moves to address underperforming positions, especially when the underlying data suggests no bounce-back is coming. What solutions there are (particularly on the waiver wire) are limited, but these are the conundrums we as fantasy managers love. Certain players are bigger red flags than others; Simpson, for instance, sits among the overperformers, but his speed makes that gap and his high BABIP less concerning. But for those of us with players at the bottom of this chart, time is running out.