Bobby Bonilla - Outfield to Third Base
Bobby Bonilla mostly played the outfield and first base coming up through the minor leagues. Heck, he had even got down on his haunches and caught more games than he did line up at third base. But after bouncing around from the Pirates, then to the Chicago White Sox in the Rule 5 draft, and then back to the Pirates, the Bucs decided to move him over to the hot corner in the late-80s. Bonilla was so new to the position the Pirates put together a Rocky IV-Esque/inspired montage video of Bonilla working out and training for third base (or at least what I assume was a production made by the Pirates themselves).
Bonilla was a big hitter for the Pirates. In the 3485 plate appearances he received, he batted .284/.357/.481 with a .365 wOBA and 132 wRC+. Bonilla won three Silver Sluggers during his time with the Bucs and finished top three in MVP voting twice in back-to-back seasons during 1990 and 1991. He also racked up 114 home runs.
Bonilla was not a very good defensive third baseman, though, with -17 total zone runs at the hot corner. He still played a decent amount of right field, as he was the team's primary right field in 1990 and played over 100 games in the grass in 1991. But he also started over 150 games at third base in 1988 and 1989.
After leaving the Pittsburgh Pirates, Bonilla would bounce around between third base, corner outfield, and first base. He spent over 50% of his innings in the field at third base but still saw over 7000 innings between left and right field and over 800 innings at first base. However, when the Pirates made him the primary third baseman in 1987, he had less than ten professional games at the position.