The idea behind this 25 man team is that it will play through an entire season without being able to call up any players that are better than some set level (be it replacement level or league average, it doesn't really matter) available to all of your opponets as well. So you are not allowed to count on any hidden gems in your farm system. As a result all injury risk and mitigation is shouldered by the 25 man roster.
So a position player that can truly play anywhere on the field is a valuable asset. There aren't many great players that have played multiple seasons worth at the defensively difficult, up the middle positions (including catcher), but there's at least one.
Selection Craig Biggio
While Biggio spent most of his career at second base, he played 428 games at catcher and 255 games in center field. While he generally wasn't outstanding defensively, he was competent and was occasionally good at second. Biggio's bat was also strong, with a career .281/.363/.433/117 (AVG/OBP/SLG/wRC+) across his career. It only appears lightweight in the context of the rest of the team. Biggio's best season was probably 1997. He hit .309/.415/.501/153 with excellent fielding.
No doubt, Biggio is a step off the pace of the rest of this team. But injuries are almost a certainty in a 162 game regular season and the combination of durability, offensive value and defensive flexibilty Biggio offers is unique and very, very valuable.
The combination of successful catcher and middle infielder is pretty much unique. If you drop the middle infielder requirement, you might consider Yogi Berra. If you drop the catcher requirement, very dangerous in my mind, you might take Pete Rose. Though neither one of these players was that much better with the bat than Biggio. If you're Whitey Herzog, you'd probably go with the Secret Weapon.