Just how integral is DJ LeMahieu’s bat to the Yankees lineup?

Ask most Yankees fans for a list of reasons that the Yankees’ offense has sputtered so far this season, and somewhere near the top they will list DJ LeMahieu’s struggles. After two MVP-caliber seasons in pinstripes in which he posted a .336/.386/.536 slash line (a 146 wRC+), the second baseman has fallen down to earth quite a bit. His .263 batting average, .339 on base percentage, and .363 slugging percentage are all among the lowest of his career. While every hitter in the lineup not named Aaron Judge, Giancarlo Stanton, or Gary Sánchez is at least somewhat responsible for the team’s poor performance at the plate, LeMahieu has a sizeable share, as he’s simply playing so far below expectations.

I’m not one to try to jump to conclusions — after all, as everybody knows, correlation does not equal causation. But it did seem like this was a narrative that we dealt with just last season, when LeMahieu missed time with a left thumb sprain. Prior to LeMahieu’s injury on August 16th, the Yankees’ offense led the league with a 132 wRC+, and after he returned on August 29th, they were third in the AL (seventh overall) with a 115 wRC+. In the nine games between those stretches, however, the team posted a measly 85 wRC+, which was better than only the Orioles and the Rangers among AL teams.

Thus far in 2021, LeMahieu has been a constant presence in the lineup. His bat, however, has disappeared for weeks at a time, to the point that you can make the case that the DJ LeMahieu who the Yankees expected has only been in the batting order for five non-consecutive weeks out of the first twelve weeks of the season. But just how big of an effect has LeMahieu’s inconsistent season had on the Yankees?

Note: Stats for this week are as of game time yesterday.

Much like LeMahieu’s performance this season, this data is all over the place. Some of the Yankees’ best offensive performances this season, like the weeks of 4/25 and 5/2, occurred during one of his red-hot stretches, but his hot start to 2021 did not prevent the Yankees offense from sputtering out of the gate.

In a similar vein, while one of the Yankees’ worst weeks at the plate occurred during LeMahieu’s worst week of the season — that of 4/25 — the team managed well enough to win a ton of games during LeMahieu’s mid-May struggles. (Although that also coincided with a stretch where the pitching staff allowed only 2.9 runs/game, which was the biggest reason for the team’s hot streak at the time.)

Ultimately, there’s not a strong correlation between any of these figures — the highest correlation exists between LeMahieu’s wRC+ and team runs/game, which is only at a 15 percent correlation. The relationship between LeMahieu’s wRC+ and weekly winning percentage, on the other hand, is mathematically zero.

Obviously, as the team’s leadoff hitter, LeMahieu is an important part of the lineup, but team offensive success depends on more than just one person. The team’s 2020 offensive stats suggest a strong correlation between LeMahieu hitting well and the offense clicking on all cylinders, but in truth, when we look at the lineups that the Yankees were running out last year, it’s a much more complicated situation. Both Aaron Judge and Giancarlo Stanton, who finished the season with a 142 and 144 OPS+, respectively, hit the injured list in the same week LeMahieu did. Of course the offense was going to struggle without its three best hitters. His subsequent return, along with Clint Frazier’s breakout, helped mitigate some of the damage and return the lineup to some semblance of its former self — although not quite to the same heights it had previously maintained.

In the end, is it important for the Yankees to get LeMahieu to consistently hit closer to his 2019 and 2020 levels? If they want to make a run in the second half of the season, absolutely. But that can only be a small part of a much larger offensive turnaround, because despite how it can feel at times, the Machine can’t do it all.