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Buy Low/Sell High: wOBA Regression Candidates (Hitters)

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Using Statcast data to predict hitters expected to surge or struggle in the near future

MLB: Baltimore Orioles at Chicago White Sox Matt Marton-USA TODAY Sports

If you’re closely tied in to Baseball Twitter, you saw the flurry of blog posts postulating the value of xwOBA and how it should be used for predictive versus descriptive purposes. If you’ve missed it and are interested, see the initial Baseball Prospectus article from Jonathan Judge, a blog from MLB Advanced Media’s Tom Tango. These arguments are for evaluating pitcher performance and whether they are better then other metrics already out there (FIP and DRA). There is still work to be done to best apply Statcast’s expected metrics to pitcher performance, but one thing we know today is that they work beautifully for batter performance. If you are unaware, a brief description of xwOBA from MLB Advanced Media’s website:

xwOBA is more indicative of a player’s skill than regular wOBA, as xwOBA removes defense from the equation. Hitters, and likewise pitchers, are able to influence exit velocity and launch angle but have no control over what happens to a batted ball once it is put into play.

So the application can be made straightforward by looking for players with a large gap in their wOBA and xwOBA values. If the expected value is higher, there’s a good chance the player puts up better numbers in the future, but if the expected value is lower, a player’s production is likely to take a step backward. Also, I recognize the Buy Low and Sell High monikers are over-used and frankly not that helpful in the fantasy baseball world, but SEO is king in our world, so until people stop using it as search terms I’m going to keep plugging the terms in there. So without further ado, let’s look at the 30 players with the largest difference between xwOBA and wOBA (15 positive and 15 negative):

Trending Up

J.D. Martinez - As if his .439 wOBA wasn’t impressive enough, Martinez’s xwOBA is .500 in the last 30 days! He also just homered as I’m writing this so expect the numbers to increase tomorrow. He’s on an absolute tear.

Stephen Piscotty - Piscotty is starting to put a brutal May behind him and has 5 doubles in his last 7 games. He’s only 52% owned on Fantrax, so it looks like he’s still rostered in most competitive leagues, but he’s the perfect add-on in a trade offer. See if you can get the opposing manager to sweeten the deal by giving up Piscotty before he gets going.

Kevin Pillar - On May 18th, Kevin Pillar’s batting average sat at .301. As of writing this it sits at .259 (although he did just homer tonight, so maybe I’m on to something). He’s been making high quality contact in the last few games, but the results haven’t matched up. Expect that to change and don’t give up on Pillar.

Trey Mancini - The .229 AVG looks atrocious, but don’t be fooled - Mancini is going to turn it around here soon. Jace Peterson and Joey Rickard are battling for the leadoff spot today, but I expect Mancini to reclaim his spot in the next few weeks.

Asdrubal Cabrera - Cabrera is having his best season as a Met, and in terms of xwOBA it looks sustainable. The chance to pick him up is long, long gone but if you did acquire him - don’t look to sell high on what appears to be a career high. Hang tight and enjoy the profit a little while longer.

Jason Kipnis - His return to relevance is actually a few weeks underway, but if he’s on the waiver wire still go snatch him up. I expect the recent production (.316/.350/.526 slash in the last 9 games) to continue.

Johan Camargo - Only owned in 29% of Fantrax leagues, I lost out on him in FAAB bidding this past week. Camargo has SS/3B eligibility and brings a lot of pop to the middle infield position. The AVG might always be a sink-hole, but he’s probably the best option on a lot of waiver wires right now.

Trending Down

Scooter Gennett - An obvious candidate here. Gennett has been crazy hot these past few weeks fueled by a .389 BABIP (career .333) and a 13.2 HR/FB% (career 8.6%), this run likely won’t last much longer.

Brett Gardner - Gardner has a history of outperforming his xwOBA, as many speedsters do, but this level of production is not likely to keep up. Gardner is a perfect sell high candidate for those looking to acquire speed and willing to convince themselves his recent power surge is for real.

Adam Engel - A bit of a shocker to see on this list, until I saw his .333/.350/.590 triple slash over his last 11 games. Unsurprisingly, the peripherals do not suggest Adam Engel will perform like an all-star the rest of the year.

Addison Russell - A recent finger injury dampens Russell’s outlook further, and what appears to be Russell turning a corner might be more of a mirage. The power hasn’t been there and his .272 AVG is fueled more by a .353 BABIP (career .303). Maybe look to sell high if news comes out the finger injury isn’t serious.

Albert Almora - Another Cubbie outperforming his batted ball profile, Almora’s outlook isn’t as negative given his speed and potential to consistently outperform his xwOBA. Still, I would not be confident investing in Almora, especially if it isn’t coming with a ton of SB production.

Jorge Alfaro - The strikeouts are really racking up for Alfaro (61 Ks in 44 games) and the rest of his production is starting to tumble as a result. I’d look elsewhere on the waiver wire if you’re a Jorge Alfaro owner (as I am in TGFBI).

Brandon Nimmo - One of the best breakout stories of the year has been Brandon Nimmo’s .421 OBP on top the New York Mets lineup. I don’t think all of it is a mirage, and I wouldn’t even rush to trade Nimmo at this point, but it is safe to say his current production levels won’t be sustainable. I do like Nimmo’s outlook for the rest of the season, so long as you aren’t expecting the production you’ve seen this far.

For more, be sure to follow me on Twitter (@BrianCreagh) or reach out via email (bcreagh119@gmail.com). Thanks for reading!