I don't believe that's even true. When people complain about so-called sabrmetric stats for offense, I don't know whether they realize how much of a dominant role is still played by good old-fashioned BA.
I'll use OPS as a simple version for explanatory purposes. Other fancy stats like WOBA and its derivatives are better respected but harder to explain, and in my experience they correlate pretty closely anyway. Sorry this is long, but I really want skeptics to consider the details.
A quick refresher for anyone not immersed in OPS. It's defined as OBP plus SLG. OBP comes from BA plus some additional outcomes (mainly walks), and it's instructive to subtract OBP-BA, although I don't know a name for it - for this post I'll call it an X factor, representing those other ways to get on base. For SLG, there is a name for when you subtract BA from it: Isolated power, or ISO, which reflects basically every extra base after reaching first before the next batter comes to the plate.
So OPS equals: (BA + X) for OBP, plus (BA + ISO) for SLG. Taken together, OPS = 2*BA + X + ISO.
Take Trevor Larnach's 2025 with the Twins for an example of this. He's a middle of the road offensive player, not terrible and not stellar, with an OPS of .727. His BA for the Twins was .250. The X factor (on base not coming from base hits) was .073 - almost exactly league average. His ISO was .154 - also league average for power, give or take. So his OPS breaks down as 2*.250 + .073 + .154 = .727 as promised.
Here's my point: more than HALF of Larnach's OPS comes from his batting average alone. 68.8% of it. He gets a little bump for the walks, he gets a little more bump from what power he offers. But it's mostly the batting average. He's typical of major leaguers.
How about Aaron Judge? His OPS is 1.144 this year. That's mostly his homers, right? Not so fast. His BA was .331, and that times two gives .662. So even Aaron Judge's OPS comes more than half (57.9%) from his batting average. That is true even with his X of .126 and phenomenal ISO of .357. (There can be a little roundoff error in that last digit.)
Arraez? This year he batted .292. His X factor for walks, etc, comes out at .035 (he never walks very much). His ISO/power is exactly .100, below par for a major leaguer. Added together, it's 2*.292 + .035 + .100, or .719. A hefty 81.2% of his OPS is tied up in his batting average alone.
2025 was a down year for Luis, though. Let's look at his career year, which was his first one in Miami in 2023 right after the trade. BA of .354, X was .039, ISO of .115. Put the pieces together and it's 2*.354 + .039 + .115 = .862 (again roundoff is off by 1 in the last digit). So that's an even heftier 82.1% of OPS earned via BA.
So what's the difference between Arraez and Judge? Well, yes, the walks and HR. (Also Runs and RBI, another pair of very old-fashioned stats.)
Doesn't matter who the player is. OPS = 2*BA + X + ISO. Batting Average is counted twice in OPS, solely by how OPS is defined. If you broke down other popular "advanced" stats like WOBA, you'd see a similar reliance on BA. Nothing else, not even home runs, matters more than BA.
BA is not undervalued by any reputable analyst I'm aware of. And rightly so. It's important. It's... just... not the final word on a batter's production.