Another good MLB parallel might be Alex Rodriguez. He didn't have the same mental issues that Sax and Knoblauch faced, but his career took an unusual turn after he signed that enormous contract with the Texas Rangers. After a few years he did something that was unthinkable in pro sports: Not only did he ask for a trade from the Rangers because he thought his huge contract made it impossible for the team to build a contending roster, but he offered to renegotiate his contract for a lower salary to accommodate other teams that might trade for him.
The Rangers had a deal to send him to the Red Sox, contingent upon a renegotiated contract. But the MLB player's union intervened and said the contract could not be renegotiated. That's how he ended up on the Yankees, who were the only team that could afford to pay him under the terms of his original contract.
That's charitable of you since my comment addressed the mental aspect of sports only. A lapse of confidence will destroy you, the yips in golf and baseball (both mentally induced) will also destroy you......as it will in any other muscle memory sport.