"Expect the unexpected" is a phrase you hear all too often, especially in sports. 2004 Red Sox in the ALCS, The US National Hockey team in 1980 against the Soviet Union, and the 2004 Detroit Pistons were all unexpected winners in their respective sports. You can't predict these, right? Well, baseball statisticians try to do just that to predict what will happen with a batted ball when it's hit.
Expected Batting Average (xBA): Replacing hit probability, xBA is the likelihood a batted ball will become a base hit. This factors in exit velocity, launch angle, and, one weakly hit balls, sprint speed. xBA also accounts for the spot on the field that the ball is hit to, which is why you see defenses shifting to where the batter typically hits. The average xBA last year was .250. Last years leaders include Howie Kendrick (.336), Cody Bellinger (.323), and DJ LeMahieu (.322).
What's important to look at here with the batters is the spread of what their actual batting average was to what the numbers said. A higher xBA than actual BA represents a player who hit to players that made spectacular plays. On the opposite side, a higher BA than xBA means the player got lucky. For example, Kendrick hit .344 last year, but his expected batting average was .336 like we mentioned. Bellinger hit .304 last year but his xBA was actually higher at .323. Keep in mind these discrepancies throughout the season as they can paint a story for you and even predict a breakout from a player. I like to see the worst in statistics as well, so here they are: Austin Hedges (.198 xBA compared to .176 BA), Stevie Wilkerson (.202 xBA to .225 BA), and Chris Davis (.206 xBA to .179 BA).
The biggest differences from BA to xBA was Marcell Ozuna (.241 BA to .288 xBA) and Fernando Tatis Jr. (.317 BA to .259 xBA).
Expected Slugging (xSLG): Much like xBA, xSLG represents what should happen to a batted ball if there is no defense around. xSLG differs from xBA in that it assigns ascending values to singles, doubles, triples, and home runs, just like slugging percentage. Using the launch angle and exit velocity, xSLG predicts the weighted outcomes and turns it into a percentage.
Leaders from last year: Mike Trout (.669 xSLG), Nelson Cruz (.643), and Cody Bellinger (.638). Last year's singles hitters were Billy Hamilton (.271), Jarrod Dyson (.296), and Mallex Smith (.297). The biggest differences were Brett Gardner (.503 SLG to .372 xSLG) and Justin Smoak (.406 SLG to .495 xSLG).
Expected Weighted On Base Average (xwOBA): Keeping with the trend, xwOBA is what a players wOBA (weighted on base average) should be minus the defense. This includes every event that leads to a batter getting on base minus intentional walks.
Leaders from last year (you'll notice a trend here): Mike Trout (.455 xwOBA), Cody Bellinger (.429) and Christian Yelich (.420). Batters who didn't want to touch first base were Nicky Lopez (.251), Stevie Wilkerson (.255) and Dee Gordon (.260). The biggest differences were Fernando Tatis Jr (.398 wOBA to .345 xwOBA) and Marcell Ozuna (.336 to .382)
Keep these statistics in mind throughout your fantasy season! I try to look at these every two weeks. It's a great way to pick up players off the waiver wire that seem to be struggling, but are just unlucky. Season to season, you'll notice players on the verge of breaking out or players that got insanely lucky the previous year. Take Marcell Ozuna, for example. He's set to have a better year this year than he did last year because his xwOBA had such a disparity. Fernando Tatis Jr should see a borderline extreme dip in his stats this year.