Potential Breakout Hitters for Fantasy Baseball - 2023 xwOBA Leaders

One of my favorite tools to look at is the Statcast rolling xwOBA leaderboard. It shows you the hitters who have improved their xwOBA the most over the last 50 plate appearances. Since wOBA (weighted on-base average) "is a version of on-base percentage that accounts for how a player reached base, instead of simply considering whether a player reached base" it can be a good indicator of who is making meaningful contact of late.

Typically, I will use the leaderboard to identify names that have been struggling or surging in terms of meaningful contact over 50 PAs (which is usually around 12-15 games) and then I'll dig in deeper to some of those names to see if the leaderboard is pointing me to anything actionable or "sticky" in terms of player results. So we're going to do that together today.

Last week, I dove into leaders in key plate discipline metrics as those were the first to stabilize, and then tried to find more breakouts with guys who are hitting the ball hard. So this will be the third breakdown I have of potential breakout hitters you could find on waivers or trade for.

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xwOBA Leaders for Fantasy Baseball

In this article, we're going to look at the 15 hitters who have most improved their xwOBA the most over the last 50 plate appearances. I'll paste the whole leaderboard below, and then dive into a few names underneath that I think might be sneaky waiver wire pickups or trade targets who you can buy low on based on public perception.

All of these stats are as of Monday, May 15th

A few players I won't cover, but you know Luis Robert Jr., Nolan Arenado, Mookie Betts, and Salvador Perez are good. I'm also not going to dive into Nelson Velazquez since he's back down in Triple-A, Chad Wallach since he's hurt, and Daulton Varsho since he remains catcher eligible and puts up stats that few catchers do, even when he is slumping.

I'll also just briefly discuss Christian Yelich to say that he is one of those aging, boring veterans that nobody realizes is as productive as he is. Yelich is hitting .262 this year with seven home runs and nine stolen bases already in 39 games. His rest of season projections have him finishing with 22 home runs and 26 stolen bases, which means a 25-25 season is well within reason and nobody seems to be talking about him.

Luke Voit makes this list, but he only starts against left-handed pitchers and is batting .221 with no home runs this season. No thanks.

Michael Massey - 2B, Kansas City Royals

A lot of smart people wanted Massey to be a thing at the start of the season, and it was confusing given that he hit .243/.307/.376 in 52 games for the Royals last year and then came out of the gate with an egregious 38.3% strikeout rate in his first 24 games this season.

If he was playing for a contending team, he would have absolutely been demoted. However, he's not, and we can be thankful for that because the 25-year-old has used the longer leash to make some key adjustments.

For starters, in 11 May games, he has cut his strikeout rate to 26.8%. He has also reduced his groundball rate by almost 9% and started to pull and lift the ball more. In fact, he's pulling the ball 50% of the time in May, which has led to two home runs and a 1.057 OPS. Massey did hit 20 home runs across three levels last year, so he has some power in his profile, which means the approach isn't a bad one.

However, his hard-hit rate has actually decreased slightly since the start of the season and, as you can see above, his xSLG has risen to just slightly over league-average, so it's not like we're in the middle of some huge breakout.

The big concerns for me are that Massey has just 34th-percentile sprint speed, so people who saw his 16 minor league SBs last year and got excited may be in for a disappointment. Also, he has crazy splits with a .368/.440/.421 triple-slash in 25 plate appearances versus LHP this year but a .187/.219/.275 triple-slash in 97 plate appearances versus RHP. Those marks are simply not enough for me to think about playing Massey outside of weeks where he sees lots of lefties.

Nick Pratto - 1B/OF, Kansas City Royals

I've written about Pratto in a few places lately, including the Samulski Sunday Tribune, which is a weekly Substack I do that looks back at the week's leaders to help identity who to spend your FAAB on; check it out! In this week's edition of the Tribune, I wrote:

It seemed like nobody cared when Pratto was called up, but it wasn’t long ago that he was the Royals’ 1B of the future and not Vinnie Pasquantino. Pratto hit 36 home runs in 2021 but struggled in his first MLB action in 2022 and we forgot about him. Well, he’s back now with more of a line drive, contact-first approach. He’s using the whole field and chasing out of the zone 10% less. He has an impressive 91.5% zone contact and just a 9.5% SwStr%.

The issue is obviously that he’s not barreling the ball as much or hitting as many home runs, but he is hitting the ball hard and sporting a .351 average. If this new version of Pratto sticks, he could be a .270+ hitter but only pop 15-20 home runs, which is still interesting when hitting in the middle of a lineup.

As a result, I wouldn't go gaga over Pratto, but it's hard to not like a guy with a 43.6% HardHit% and a zone contact rate over 90%. Especially when that player hits 6th for a team that has the best wRC+ in baseball in May. Yes, the Royals!

J.D. Davis - 3B, San Francisco Giants

I think most people, myself included, wrote off Davis because "the Giants platoon too much." Yet, Davis has started seven straight games and 10 of the last 11. With Wilmer Flores basically only slotting in at DH against left-handed pitchers and Evan Longoria out of town, more playing time has opened up for Davis. That could all change with Brandon Crawford coming back from injury on Sunday and Casey Schmitt perhaps hitting his way into more at-bats.

Still, Davis is the primary 3B for San Francisco and has been hitting the ball well, going .293/.364/.488 on the season with seven home runs and 22 RBI. He's also seen his zone contact jump over 12% to 83.2% while being more aggressive in the zone. He seems to have made the contact gains by taking more of a line drive approach, cutting his launch angle to 8.9, which is his lowest since the COVID-2020 season, and posting a career-low 22.2% fly ball rate.

Since Davis has a 52% HardHit rate, 93.3 mph average exit velocity, and the highest pull rate of his career, some of his line drives have left the park, but he's less of an all-or-nothing type of hitter with this approach. That's supported by his .300 xBA (99th percentile) and .376 xwOBA (87th percentile).

You may only get a 20-home-run season out of this version of J.D. Davis, but he could hit .270-.280 with good counting stats in the middle of the Giants' lineup, so perhaps now is the time to try and get him if somebody is concerned about what the return of Crawford will do to his value.

Matt Thaiss - C, Los Angeles Angels

This is just for two-catcher formats or AL-only formats, but I think Thaiss is worth your attention. With Logan O'Hoppe having shoulder surgery in late April, Thaiss stepped into the starting lineup and it's not really much of a committee. Thaiss has started five of the last six games, including one of two against a left-handed pitcher in part because Chad Wallach, who was splitting time with him, is now out with a concussion. The Angels basically have nobody left.

However, even if that weren't the case, Thaiss is hitting .291/.385/.382 with a career-high 9.8% barrel rate. He's being a little bit more selective, which has led to a lower strikeout rate and SwStr% rate. He doesn't really provide any pop or speed, but if you're in a deeper league that simply needs at-bats from your catcher, Thaiss is now firmly in the mix.

UPDATE: After submitting this article, Wallach was activated from the IL; however, he is a career .205 hitter and shouldn't threaten Thaiss' playing time too much. 

Harrison Bader - OF, New York Yankees

This is cheating, but Bader is the next player on the leaderboard, and I wanted to fit one more intriguing name onto this list.

The center fielder has always intrigued fantasy managers with his power/speed combo but has never played enough games to make it count, only breaking 100 games played once since 2019. Yet, Bader has come out firing in his first 12 games of 2023, hitting .333/.378/.643 with three home runs, 11 RBI, and one stolen base. He has also hit 5th or 6th in the Yankees lineup in basically every game he has played, which gives him counting stats value.

It's too early to read into his minuscule 6.7% strikeout rate or his fairly average 7.7% barrel rate or his career-high 53.8% flyball rate. What we can say is that this is a player with 88th-percentile sprint speed, who has shown the ability to pull for power, and is currently playing every day in the middle of a lineup that has the potential to be fairly strong. He deserves to be rostered in most leagues just for his 20/20 upside alone.

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