Votto is one of the hardest workers in the game. He spends hours watching film and has made adjustments his entire career. He's too good of a hitter (trust me, it's a large sample size) to not figure things out sooner rather than later.
What makes Joey better than most is his slumps don't look like everyone else's. He's not flailing away while he tries to find his swing--he's still getting on base at an MVP-like clip. I'll take his slumps over Bruce's every day.
Nothing to worry about.