Exit velocities and launch angles are strong indicators of likely success, but sometimes hitters’ results don’t quite match up with their quality of contact.
At MLB.com’s Baseball Savant pages, “expected” stats tell us what results a player’s exit velocities and launch angles normally would bring.
The Cubs’ Cody Bellinger has a batting average, slugging percentage and weighted on-base average well above normal for their contact quality. Teammate Dansby Swanson has had better contact than results.
Whether the cause is the wind or other elements, quality of defense and positioning or just plain chance, hitters don’t always get what they deserve.
Results mostly mirror expectations within a few percentage points. Big-leaguers have hit for a .249 batting average, very close to the .247 expected BA. A .415 baseball-wide slugging percentage is just above the .411 xSLG. The .319 wOBA is just under the .321 xwOBA, where wOBA is a weighted average of all offensive results from double plays to home runs.
Most players finish with numbers close to norms for their contact. A look at Cubs wOBA vs. xwOBA finds Christopher Morel (.342, .339), Nick Madrigal (.294, .294), Seiya Suzuki (.348,.349) and Ian Happ (.342, .344) all within three points of their expected average.
Bellinger has been an outlier. Among players with at least 250 balls in play, the positive gap between his .373 wOBA and his .326 xwOBA is the fifth-highest in baseball.
That has come in a season when his 87.7 mph average exit velocity ranks 212th in the majors and 4.7% barrels vs. plate appearances ranks 170th.
Bellinger has outperformed expected averages in BA (.311 vs. .268) and SLG (.534 vs. 437) in by far his best season since he was the National League MVP with the Dodgers in 2019. Then, he had a .415 wOBA and 7.8 Fangraphs WAR. Hampered by injuries, Bellinger sank to wOBAs of .337, .237 and .884 with WARs of 1.4, -1.0 and 1.8 before recovering to .373 and 4.0 this season.
Nico Hoerner also is on the plus side, but not as extreme as Bellinger, with a .324 wOBA vs. .312 xwOBA. Including his 419 plate appearances for the Nationals, as well as 136 for the Cubs, Jeimer Candelario’s .347 wOBA far exceeds his .320 expectation.
On the hitting in tough luck side, Swanson has a .249 BA, .421 SLG and .327 wOBA, well below “x” stats of .258, .464 and .349. His 89.3 mph average exit velocity and 7.3 barrel percentage outrank Bellinger, but he hasn’t had the same outcomes.
What usually happens when a player performs far above or below expected stats is that results mirror quality of contact from that point forward.
If Bellinger’s quality of contact produced a .326 xwOBA again next year, he’d be far more likely to put up a wOBA within a few points of .326 than repeat his .373. That’s still above the major-league average. With strong defensive skills in center field and first base, Bellinger would be valuable at that level, if not quite the star performer of 2023.
