Decreased avg EV and hard hit rates would very likely correlate to decreased performance, but not necessarily underperforming your xStats. You can underperform if you are slow, or have a suboptimal balls spray distribution chart. A good example is Matt Chapman hitting 400 foot bombs to dead CF, where even a 350 foot wall scraper gets the job done to LF. The opposite of Matt Chapman 2023 is Isaac Paredes and Davis Schneider, guys who sell out for pulling balls with good/mediocre EVs for good results, that don't necessarily have the physical tools to hit bombs all over the place ala Aaron Judge, Yordan Alvarez, Juan Soto types.
You can also technically hit balls softly and have some success, by hitting a bunch of weak infield singles or little looping line drives over the defense, those balls are simply too hard to defend. Sometimes you'll see an 80 mph soft flyball have an xBA of like .990 because those balls are nearly impossible for defenders to catch. This is a very niche skillset and not a lot of players can succeed consistently with it.
Springer has never been much of an avg EV darling, where he made his money is on barrel rate and sweet spot %, which have been declining the last few years. With that said, his xWOBA right now is in the 69th percentile, he still doesn't chase much and has been better at drawing walks in the early going, with an elevated sweet spot rate. These are probably the kinds of adjustments he'll have to make as his raw power declines, and he can still be an average to slightly above player earning more than he's worth.