There are stat lines, there are odd stat lines, and then there’s what Yasmani Grandal is doing in 2021. The White Sox catcher is hitting .136, a far cry below his career .240 batting average entering ‘21. But that’s not even the half of it. He’s slugging .364, with an on-base percentage higher than that -- at .391. It helps that he’s walking in 26.4% of his plate appearances.

He also has a 126 wRC+, which would be the second-highest of his career, behind a 144 mark in his rookie year in 2012, when he played in just 60 games.

To be clear -- Grandal is still an above-average framing catcher, and he's hitting the ball hard and getting on base. He's helping his team win when he plays, but, separately, this atypical combination of numbers deserves a closer eye.

There’s a lot to unpack here. Let’s dig in.

Difference between on-base percentage and batting average

Currently, Grandal’s batting average is 255 points lower than his on-base percentage. He isn’t a qualified player -- he’s currently nine plate appearances short -- but for the purposes of context here, we will compare it to qualified seasons, as he’s likely to finish the year in that category.

The largest difference between OBP and BA in a single, completed season for a qualified player? 247 points, by Barry Bonds in 2004, when he hit .362 but had a .609 OBP thanks to a record-setting 120 intentional walks.

The only other instances of a difference of 200-plus points are Bonds in 2002, with a 212-point difference between a .370 average and .582 on-base, and Yank Robinson in 1890, with a 205-point difference (.229 batting average, .434 on-base percentage).

Of course, none of those batting averages are particularly close to Grandal’s .136, and the idea that a player hitting that infrequently could still reach base with some consistency is part of the point here. The highest on-base percentage in a qualified season for a player who hit .200 or lower is .368 by Jimmy Sheckard in 1913, when he hit .194. Thus, Grandal’s current numbers would set that mark, too.

High wRC+ with low batting average

wRC+ quantifies run creation and normalizes it. Walking certainly helps one’s cause with respect to the metric, but there’s no question of the importance of hits, too. It should come as little surprise that having a wRC+ of 100 or better -- in other words, league average or above it -- coupled with a low batting average is pretty uncommon.

Only three players in the modern era (since 1900) have had a 100 or higher wRC+ in a qualified season where they hit .200 or lower: Carlos Pena in 2010 (.196 batting average, 105 wRC+), Matt Olson in 2020 (.195, 103) and Max Muncy in 2020 (.192, 100). And of course, Olson and Muncy did that in a shortened season, so they might have gotten above the .200 mark had there been more games. And if we extend prior to the modern era? We only add Billy Nash in 1884 (.199, 105) to the list.

How exactly is Grandal doing this?

Much of the key here, as you may have already guessed, is walks. As noted above, Grandal has a 26.4% walk rate. The only player to post a walk rate that high in a qualified season is Bonds, in 2004 (37.6%), 2002 (32.4%), 2003 (26.9%) and 2001 (26.7%). That’s right -- Grandal’s current walk rate would be the fifth-highest we’ve ever seen in a qualified season, behind Bonds’ four straight MVP seasons.

Bonds got those walks by being the most feared hitter in the game. Grandal? Slightly differently. He’s swinging just 25.7% of the time, which would be the lowest of his career. FanGraphs has swing rates tracked back to 2002, and the lowest by a player in a qualified season in that span was 30.6% by Brett Gardner in 2010. So when we say Grandal isn’t swinging, he really isn’t swinging.

As for the batting average, a .120 BABIP certainly isn’t helping matters -- the results when he makes contact are not too positive, which encourages him not to swing. A career-low percentage of pitches seen in the zone factors in, too.

Can this continue?

Common logic, even before digging into the numbers, indicates that his stats can’t continue to be so disparate for the entire year. His BABIP, as noted above, is likely to level off more towards the league average.

And it’s worth noting, as an added oddity, that he’s crushing the ball on the contact he does make. Grandal has a 54.4% hard-hit rate on his 57 batted balls, which would be his highest since Statcast began tracking in 2015. That’s part of how six of his 12 hits this year have been home runs -- which do also help his wRC+, by the way.

His expected stats, which are based on quality of contact, plus strikeouts, indicate that his batting average and slugging percentage should be higher, at .177 and .408 expected, respectively. But that .177 xBA is still a low number, likely due to the part of quality of contact other than exit velocity -- launch angle. Grandal has a 26.3% sweet spot rate, down from 38.1% last year. That means that less of the contact he’s making is in the launch angle sweet spot zone (8-32 degrees). If he’s hitting the ball hard, but directly into the ground or skied for a popup, that’s going to lower both his real-life and expected batting average.

From his batting average to on-base percentage to slugging and hard-hit rate and wRC+, there’s no question that Grandal has been putting together an atypical stat sheet in 2021. If it does continue at this rate, it has the potential to be unprecedented.